I took the gear box on the gearmotor apart. All of the little plastic gears seem to rotate and mesh just fine, except for a little backlash, which should be expected from a plastic gear train. I think its safe to say that the problem is with the motor itself. Meade probably got a bad batch of them, causing this problem for a number of new owners. When I put my finger on the motor while its tracking, I can feel a lot of vibration.

I'm sure there is no way Meade would send me a new motor under warranty, even though that would be the logical, cost effective thing to do. It looks like its real easy to remove and replace.