My driver-side door lock recently failed. It would get stuck in the locked position. My remote wouldn't unlock it, and the key didn't seem to work either. The manual lock in the door panel worked fine, however.

After pulling of the door panel, and ultimately removing the latch assy (three torx heads at the door jam) I found the problem.

1. The latch assy was dirty and the grease had dried out, and was a bit sticky, making it difficult for the key and the power solenoid to move.

2. As a result of above, the small white rubber "bushing"? between the solenoid arm and the latch ripped, and the arm poped out of the bushing.

I cleaned everything up and lubed it. Then I removed the white bushing, flipped it 180, then applied a dab of RTVto keep it from popping out.

Its a real shame that this problem was caused by a little rubber part that probably cost about 1 penny. It seems that most of the problems I've had with my Z are a result of GM not paying attention to details. I really hope things have changed for the better on newer GM products.