Alright, this is a little off the beaten path, but I figure some of us out there may have American Flyer trains. I have three American Flyer steam engines, two of which are probably 40 or 60 years old, the third newer with a plastic body, and newer mechanical/electrical components. One of older units used to run fine, but now it seems to have a motor/linkage issue. The other two never ran, and by bench examination, they all seem to suffer the same problem.

The motor will not turn driving linkage, regardless of supply voltage. Trying to rotate locomotive driving wheels helps very little to not at all. I have experience in repair of many things, so I'm not too afraid of digging in deep here. I have done the following: Carefully disassembled armature, stator, worm and bull gear, and removed driving rods from driver to eliminate extraneous friction or binding while testing. Cleaned, inspected and lubed/graphite where appropriate. No heavily worn or excessively loose parts noted. Field and armature windings appear to be undisturbed, but I have not applied a meter, and don't know what the OEM ohm reading should be for the windings. All parts appear to be intact.

Reassembled and rotated by hand the motor armature and it drove the worm gear/driving wheel easily and without binding. However, applied effort to the driving wheel to attempt rotation of the armature caused it to lock up. Some slop in armature end play noted. No spring loaded or tension device found for armature- I don't know if it should have end play or not- one of these has a felt insert on the armature shaft bearing. Audible and aromatic effort noted on motor when current applied over a range.

I have a feeling this is a mechanical issue rather than electrical. If I had to guess, I'd say there is an issue with the worm gear and armature backlash, or some other cause for lock-up and binding. The worm and bull gear do not exhibit unusual wear. But, is it possible that the armature contacts may be incorrectly seated? They seem OK, but I imagine it wouldn't take much for a problem there.

Never having repaired these, the possibility exists that I've missed something key. Question: What is the common failure of these engines in this regard? And, are replacement parts available for the prescribed remedy?

Finally, can anyone direct me to a solution? I Googled this issue/topic/troubleshooting several times today, but came up with nothing useful.