I have an HO scale Bachman GS4 that is about 7 years old, which has run very well until the last time I put it on the track. It now has a grinding noise when running at slow speed. When it is running fast the sound is not noticeable. I do not know if it goes away or is just covered up by the normal noise.
I removed the drive wheel cover plate and lifted the center drive axle so that its gear was not engaged to the rest of the gear assembly. I could still hear the sound at slow speed. This seems to indicate that it is something in the motor or worm gear assembly.
Any suggestions about what to do next?
oil the axle ????
Can you oil the worm gear assembly.