I have just gotten an old Aurora HO scale Model Motoring set. I am a very active Model Railroader so I have some knowledge of how this should work. I have approximately 10 cars about half of them are the pancake motor the rest I don't know what they are. None of them will run. I have taken one of them apart and cleaned it checking all of the contacts and as far as I can tell it should run. what might I be missing? Les.