I recently sent my 4-8-4 to Bachmann for repairs. Sadly it was too old so they replaced it with a spiffy brand new 4-8-4(which was awesome) however, here is the problem. It stops cold as if it's getting bound up or something. I'm using 11.25 radius as recommended and my diesels/ 0-6-0  run fine around the track. The 4-8-4 will stop cold on straight, curve ( left and right). Bachmann just wants to replace it but it's BRAND NEW......

Thoughts?