This is all very useful, thank you. These are very old cars--15 years, maybe--and two of them were simply stored in Jim Strong's basement in the original plastic. The other two Jim or Kevin mdafied ingeniously (see below). The problematic ones have the plastic axle metal wheels, which roll very badly. I just took the trucks apart and lubed them throughly and also filed a place on the trucks where the truck corner hit the truss rod bolster on the diner car. I did a very brief quick and dirty test (it's raining here) and they rolled much more freely. I;m planning to cut the tangs off and reinstall them shorter, but not prototypically short.
The other two car had their interiors removed, to lighten them, and had plastic wheels installed. They also had the coupler tangs replaced with dramatically shorter tangs, and they couple (aristo couplers) very very closely. One of them has an ingenious spring system, so that the coupler can be pulled out for coupling but then springs back to hold the cars close. These cars track well but come uncoupled. It may be because they couplers sat untended for fifteen years. I'm going to put metal wheels in them and replace the couplers with new aristo couplers, and then maybe try to get the lights working and fake up an interior
