I.                Carefully Unpack the Model

A.               Packaging is not a strength of many eBay sellers, too many trust in UPS, Fedex, USPS and let the model rattle around inside an empty box.

B.               If the model is not firmly supported by the foam inside the OEM box or if the foam has deteriorated, proceed cautiously looking for loose parts. 

C.               A can of Dustoff is useful in clearing debris after the model is unpacked; pieces of foam can get in everywhere.

D.              Visually inspect for damage and/or missing parts, look for structural damage, broken solder joints, loose driver tires

E.               Separate the engine and tender if they were shipped connected with plug-in cables.

F.                Press on the drivers to see if they are sprung, if one set of drivers does not move, a driver spring may be missing or there may be a severe mechanical problem, investigate before testing.  Use a small straightedge placed on the driver treads to check that all the drivers will press equally against the rails.  Turn the model over and check the other side.  If a driver shows high or low on the straightedge, do not operate until corrected.  Look for valve gear that has been pushed up or down out of position or has become disconnected; again, do not operate until corrected

II.              Testing the engine without the tender

A.               Using a DC power supply with voltage (15volt DC) and amperage (500 milliamp) meters connect one test lead to the engine frame and the other to the wireless drawbar.

B.               Roll the locomotive drivers back and forth across your hand, the drivers should have enough play to move a few degrees in either direction.  If the drivers other than the geared axle are frozen, skip this section.

C.               With the model on test rollers or suspended so that the drivers are not touching;  Slowly apply power to the engine.  If the model runs smoothly at all speeds in both directions, proceed to Testing the Model on the Test Track.  If the model does not run and draws zero current, then the wiring is broken somewhere and the engine needs the superstructure removed to trace the electrical path.  NOTE Some models should never be run upside down because the valve gear will move out of position and jam the mechanism.  Typically the problem is where the piston valve rod attaches to the valve gear inside the valve guide.  Some builders omit the small rod or do not clamp the rod in the valve guide, allowing the valve gear to move out of position when turned upside down.  2nd NOTE This can also happen with normal running, correct if possible.

D.              If the model lopes at very low speeds but then runs smoothly with more power, the flexible tubing needs replacement and alignment.  After replacement with silicon fuel line tubing, proceed to Testing the Model on the Test Track

E.               Observe the amp meter at various speeds.  A model with a can motor should not draw more than 150 milliamps during this test.  A model with an open frame motor should not draw more than 500 milliamps.  For model with excessive current draw, proceed to the Excessive Current Draw section.

F.                If the model is excessively noisy, it is most likely due to an older, possibly worn out open frame motor or poor gear mesh.  To replace a bad or worn out motor, consult an on-line repowering guide (mine can be found at www.shastasprings.com).  Gear noise can be due to poor gear alignment, spur gear towers, repair using the wrong gear pitch; or excessive gear wear due to poor gear box design or the wrong parts.  Excessive noise and current draw will likely require gearbox repair by replacement, consult a repowering guide before proceeding.

G.              If the model has an obvious bind with each driver rotation; there is likely a driver quartering problem.  Perform a quick visual check. By hand rotate each driver so that the counterweights align on one side; carefully turn the model over, the counterweights should be parallel, about 90 degrees from the alignment on the other side.  NOTE the geared axle normally leads in the direction of the rotation due to the slop in the models side rods.  Models failing this visual test will need to have the quartering checked.

H.              By reaching this step you have an almost fine running model with a hesitation (or lope) at all speeds.  This normally indicates a mechanical bind in the running gear.  Look for crossheads hitting pistons, valve gear hangers, misaligned crosshead guides, poorly soldered or loose guides.  Look for broken, detached or bent valve gear components.  Look for side rod and main rod interference with eccentric cranks, side rod screws, other rods.  Move the drivers side to side in the frame; sometimes the interference occurs only in one direction when the drivers move to one side.

I.                 This model is a hard one to diagnose,  99% of problems will have been found by this step.  Indications are that it is a hidden defect, such as broken solder joints in the frame, or wiring interference, that can only be discovered by careful disassembly.  Proceed with caution.

III.            Testing the Model on the Test Track

A.               Connect the test DC power supply used before to the test track.

B.               Place the engine on the track, apply power, look for shorts.  Current draw should be zero.  IF there is any current draw then you may have failing insulation in the wheelsets or drivers, brass detail parts touching an insulated wheel flange.  Brass brake shoes are a very common culprit for this.  If you have brass brake shoes and a short, remove the brake shoes before proceeding.  Driver insulation can be compromised by conducting oil saturating the paper insulation between the driver center and driver tire.  At 12 volts DC, smoke may be seen from the insulation actually burning, there may be smoke burns on the driver tire.  The driver will have to be repaired/replaced before proceeding.

C.               Place the tender on the test track by itself.  Again apply power looking for shorts.  If the engine and tender have not been modified with electrical enhancements such as DCC, etc...; all insulated tender wheels should be on the same side.  On models with four wheel tender trucks it can be very easy for one set to rotate 180 degrees and cause the tender to short itself.  Some builders installed a pin to prevent this tender truck rotation.  The insulated tender wheels should be opposite the insulated wheels on the engine so that they rest on opposite rails.  Check for conductivity between the tender axles and the wireless drawbar pin.  Some builders coat the pin with insulating varnish.  Correct if necessary.

D.              Connect the engine and tender on DC models.  (Further testing of DCC models is outside the scope of this discussion)

E.               Run the model back and forth on the test track, observe current draw. If the model does not draw current, there is a break in the electrical path.  See the section on Checking the Electrical Path to the Motor.  If the model does not run smoothly; Repeat the testing steps D-H of Section II.  Current draw should not increase more than 10% when running the engine and tender on the test track. 

F.                Hold the model by the tender and give enough power to attain driving wheel slip on the test track.  For a can motor this should not be more than 400 milliamps, for a coreless motor  no more than 150 milliamps.  If the motor stalls the locomotive is underpowered and the motor will eventually fail.  Note on OMI diesels this test will likely snap (break) the fragile OMI 2mm shaft universal set, replace with the Hobbytown 2mm universal drive for reliability.  If the model runs fine you are done. Congratulations�

G.                The test track will show problems best described as "tracking".  The engine may wobble or hunt down the track.  This behavior is common with 0-4-0 tank engines; but with larger locos is normally due to out of gauge wheels or wheels not squarely pressed onto their axles.

H.              Check to see if all the drivers are on the rail at all times.  Stiff or poor springing may make one driver set high-bottom on the track, allowing the engine to rock back and forth when weight is applied on either side of the offending driver set.  This is fairly common on models with torque arm motor mounts that do not allow free movement of the geared axle.  Sometimes the engine weight and/or the neoprene tubing also prevent the geared axle from moving.  Repowering guides provide some tips on freeing up the geared axles.

I.              Frankly there are some "bad models" that have been produced.  Typically these are very early models, produced in the 1950s in Japan or in the late 1970�s in Korea.  Check a brass guide for the production date and builder location for the model. 

J.                 Some highly desirable and valued models suffer from poor craftsmanship and quality control.    Caveat Emptor.

IV.            Excessive Current Draw (Advanced Evaluation)

A.               Carefully remove the engine frame from the superstructure, look for items that may impact the rotation of the drive shaft or press upon the motor or gearbox.  Common culprits are wires, boiler weights, brass parts, etc�

B.               Test just the mechanism with the DC power supply.  If current draw is now normal, there was an obstruction you missed during the visual inspection of the previous step.

C.               Visually inspect the drive train from the motor to the gearbox.  There should not any sharp bends in the drive train.   Flexible tubing will markedly increase current draw if there are bends; sharp bends are much worse.  Good universal drives can correct this problem.  Disconnect the motor from the gearbox.  If current draw is still high, you have a bad motor that must be replaced.

D.              If current draw for the motor is normal, reconnect the motor and gearbox.  Disengage the gearbox from the geared axle by removing the gearbox cover and raising the gearbox slightly until the drivers spin freely.  Test again, if current draw is still high, you have a bad gearbox.

E.               If the drivers do not spin freely with the gearbox disengaged then something in the frame is keeping the drivers from turning. Corrosion in the bearing is commonly seen in older models, the steel axle rusts  inside the bearing.  This freezes the axle inside the bearing in the worst cases, in milder cases it creates a heavy drag on the mechanism.  The problem can be simply fixed in most cases by removal of the driver set from the frame, soaking the bearing with an anti-corrosion lubricant and then moving the bearing to the center of the axle,  The corroded axle is now exposed and can then be polished with a polishing strip or extra fine emery strips.  Use an electronics contact cleaner to clean off remaining particles if you do not have access to an ultrasonic cleaner.  Lubricate with an anti-rust lubricant before sliding the bearing back into position.

F.                Look for screws that when tightened may rest against a driving axle.  Pilot and trailing truck screws are frequent offenders as their threaded holes in the bottom frame cover may be directly over an axle.  Replacement with the wrong screw can contact the driver axle, locking up the mechanism or creating considerable drag. 

V.             Checking the Electrical Path to the Motor   

A.               Check the tender first, look for additional wires or wipers indicating the previous owner had problems providing a circuit from the tender. 

B.               Many brass models received a clear lacquer coat to slow oxidation; it can also be an effective insulator.  The following surfaces need to be cleaned to bare metal:  Drawbar pin, tender frame truck bolsters, truck bolsters, grounding tabs on engine and tender. 

C.               Use an Ohm meter to locate opens in the electrical path. Wiggle wires as you test them, they may have internal breaks causing intermittent opens.

D.               Clean all conducting surfaces, wheel treads, bolsters, track, and test clips.  Alcohol used with a Q-tip removes most junk with little chance of damage to the wheel; never use a wire brush in a Dremel.  Some wireless drawbars struggle to maintain tight contact.  I've used PSC push together drawbar HO-3117 with success to upgrade poor drawbars.

E.               Polish wheel treads, bolsters, using a jewelry grade extra fine (320 grit) polishing wheel in a Dremel.  Hold the wheel at a slight angle to the wheel flange to polish away tool marks on the wheel tread.  To quickly polish driver treads, the wheels must be turning in the opposite direction of the polishing disk. 

F.               Tender trucks frequently have small bearing surfaces in the truck sideframes that are easily clogged with dirt and oxidation.  Clean the truck sideframe bearing surfaces with an Electronics grade Contact Cleaner and lubricant.  Burnish the bearing surfaces using the same 320 grit polishing wheel.  Hold the truck sideframes firmly between your fingers and press the polishing wheel against the center of the wheelset axle.  This will raise the RPM of the wheelset well over 100,000 rpm and quickly burnish the bearing surface in the truck sideframes, improving electrical conductivity and reducing rolling friction.

VI.          Seek help online

A.               There are numerous online resources available.  NWSL has much of their catalog online including some repowering guides for specific models.   At www.shastasprings.com I have repowering guides for KTM engines as well as PFM Shays and Climaxes.

B.               Join on an on-line group like RepowerAndRegear on Yahoo Groups.  Members of this group have repaired and or owned a large variety of models and can provide suggestions for getting that engine running again.  Check the archives for discussions of your model.

C.               Evaluate the seller; it isn't hard to test track a model.  If an online model railroad retailer can't test a model with a DC power supply and test leads or guarantee that the engine runs, don't pay top dollar or shop elsewhere.