Finally getting a chance to look at this. Got this nice 2010 set of CP F3's (6-34582) from a forum member last year. It has had an issue where it just seems to stop moving, mostly in corners, for no apparent reason. After much messing around I finally figured out that both power trucks seem to be slipping, though the motors are turning just fine. The wheels just don't turn. You can rotate either motor flywheel by hand and if you hold the wheels the motor still turns. Its as if the worm gears or something are slipping on the motor shafts. The interconnecting gears between the axles on both trucks are fine.
I am hoping that someone else has been through this and can tell me what the problem is, and the fix.
Thanks, Rod