The field coil could be open or have some shorted windings. This would cause the condition you describe.
This is a common problem with that type of motor. The stakes around the motor get loose and shift. Open the engine and examine the stakes. They look like thin layers of metal that surround the motors commutator. If slightly out of alignment the commutator will not spin freely it will groan and stick.
The fix is to carefully realign the steaks and tighten down the rivets that hold them. In some cases a hammer whack will realign and in others you have to drill out and remove the rivets and completely re-secure them.
Make sure the wheels, pickup rollers and track are all clean. Take off the body and remove the brushplate from the motor. Pull out the armature and clean it, the brushes and copper commutator with naptha (lighter fluid). Oil the axle bearings and gears, and roll the chassis back and forth to insure free rolling and no binding. Oil the bottom motor bearing, add a little grease to the armature worm and reinstall the armature. Assemble the brushes and brushplate, and add a drop of oil to the top armature bearing where the shaft extends out of the brushplate. Try your loco again. Check the proper functioning of the reverse unit. If you still get uneven running, unsolder the wires (green and yellow?) from the field coils to the reverse unit. Ground one of the wires and apply power. The motor will run in one direction. Unground the wire and ground the other wire and apply power. The motor should run just as well in the other direction. Make sure it runs properly both ways before continuing. Resolder the wires and check for normal operation. If the loco still has problems, you may have a bad e-unit that needs servicing.
Larry
Howdy all,
I have a Lionel 8351 Alco. Up until a few weeks ago, it ran perfectly. Now it won't run forward. With the voltage all the way up, it makes an eerie growling noise. In reverse, it will only crawl with the voltage all the way up. It makes the same noise. Any ideas on what is going on?
Thanks,
Brody
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