Hi, I bought 2 Spectrum K4s at a local train show.  Both run great on straight track.  I added Tsunami sound to both and they sound awesome when double-headed.  The problem I am having is that one of them (3750), when going round a 22" curve, the front truck frequently shorts to the frame.  The other (1361) has no problems.  I can remove the front truck and both run great, but it does not look right.  Swapping front trucks between the locos has no effect, 3750 still shorts to the frame.  Has anyone run into this problem?  Any ideas?

Thanks,
John