Hi Grampstrains,
Thanks for the reply and advice! I will oil and grease it all up, also, I want to put a switch on the smoke unit or change the light since they seem grounded together.
I put a little oil on the worm gear (will grease it later). So with power applied while holding in midair, I ran it in reverse for a few minutes at about 14 volts, and then forward, so now much improved. Through the cab window, I can see the commutator jumping around a little in reverse, fairly stable in forward. So perhaps a little washer might help.
(40 years doesn't seem that long to me!)
Thanks! Take care, Joe.
P.S. I am glad it doesn't have traction tires; I only pull short trains, lightweight rollingstock. J.