My front passenger door does not lock, either by key or knob.

I tried to re-synchronize. I don't know what that should have done, but it made no difference.

I removed the door panel. I don't see any obvious problems.

The symptom is that the door knob twitches when I attempt to lock or unlock from the drive side lock, but it seems to be blocked from moving downwards, either electrically or manually.

Is there a detailed process I should use to diagnose the lock actuator solenoid?

Other suggestions?

Thanks,
- CarlD trimagna@yahoo.com