Well, in absence of any more responses, I went ahead and completely disassembled the rear window assembly. Indeed, the gears had somehow become misaligned. If you remove the entire power window assembly and then remove the electric motor, the loaded spring will shoot out and nearly take out your eye. Before removing the motor, note the position of the spring so that you can reload it correctly. Once the spring has shot across the room you can examine the gears and see that there are alignment markings so that the lift arms are aligned. Mine had slipped two teeth. The tough thing is to reload the spring. If you have 3 arms or a buddy, this will be much easier. If you rotate the arms about 270