Kato SD40-2 motor problem

[Herc Driver]

Hi Guys...

I've got an Nscale SD40-2 made by Kato with a rear truck that doesn't work. Let me explain...

Both front and rear wheels turn (in fwd or reverse) as long as the front truck is conducting power and touching the rails. As soon as I remove the front truck wheel set from the rails, the rear truck wheels won't turn and the rear light doesn't illuminate. I noticed this when I was trying to clean the wheels...I could clean the rear wheels on a cleaning cloth when I allowed the front trucks to rest on the rails and conduct the electricity to the motor, but when I tried to clean the front truck wheel set, the rear set didn't seem to conduct the electricity. Has anyone else noticed this on this particular engine?

I'm going to pop the shell off today and try to see if there's an obvious problem...I've already checked the wheel gauge (all the wheels were gauged properly) and if the metal conducting strips were making contact with the wheel axle point (they seem to be). I'm no motor expert, but it seems strange that the rear wheels would work only with the front truck picking up the power from the rails. I don't have any other engine like this where only one truck operates as long as the front truck is making rail contact. The rear light illuminates and the rear wheel set turns just fine (when in reverse of course) as long as the front truck is on the rails. And when the front truck is making contact with the motor running in "forward", the front light illuminates and both front and rear wheel sets turn normally.

Any ideas?

I've already tried to properly explain this condition to whomever is reading the email at Kato...but haven't heard a reply yet...so I thought I'd seek the expert advice here!