Kato SD40-2 motor problem

[Herc Driver]

Good ideas and I'll try them. This is a straight-DC engine for now. As far as I can tell, the electrical strips are touching correctly...but it's a challange to prove that's true even with a light and magnifying glass to see the small parts. It seems strange that power will run to the rear wheel set with the front trucks on the track (which should prove the motor turns both front and rear trucks). The engine has never been dropped (at least not while I've owned it). So I'll pop off the shell and see if there's anything not touching that should be to properly conduct the electricity. It pulls fine, and if I didn't get the idea to clean the wheels, I wouldn't have noticed there was a problem.