Sounds like a lot of work to avoid buying the available power truck.
Except that I had pulled the parts and cleaned them, disconnected the motor and was running the locomotive with just one powered truck and the same thing happened to that truck. The disassembly and cleaning is done and I'm looking at about $12 in retaining compound versus $82+shipping in new trucks.
Edit to add: As much as the cost savings, the idea of tossing otherwise perfectly good parts, particularly when there's a straight-forward-sounding fix, doesn't sit right with me. If I mess the DIY repair up, then I won't mind picking up new trucks.