Hello all, I'm fairly new to the train world so please bare with me. I recently acquired a older 36 ton shay and the trucks were shot, so I replaced them with spectrum #88999 die cast trucks and the train ran smooth for about six laps (64' of track) and then started jerking real bad and train looses most power like its shorting out. My trainpower 6200 controller shuts of the circuit, others engines work fine. My track is brass and very clean. When I remove the trucks from the chassis and run them by them selfs they run very good with no problems but when installed back on chassis same problem occurs the train is not sound equipped. I've tried running the train without the two wires to the trucks and no difference. Is there an internal short somewhere? Does the chassis pickup power from the trucks other then through the wheel pickups? Just weird how the trucks work good when not on engine. Anybody else have this problem? Please help. Thanks