Atlas Nscale SD60 Short Circuit Problem

[Steamtrains]

When locos go "crazy" on the track, it's a sure-fire indication (with the Zephyr) that you have a short somewhere. If everything else works fine, it's got to be in the locos. If you've got a multimeter it should be easy to track down. Check conductivity from the wheels to the opposite side on the frame, and between the frame and the motor leads.
Good luck..!!