Passenger Door Lock Troubles

[gulflex]

I have a 2000 GMC with automatic door locks that has just lately has not been locking on the passenger side only. It sounds like it clicks, but then nothing. I am afraid that it is the door lock actuator. I went by my local GMC dealer and the man there told me to take the door panel off and see if there was not anything else wrong. When I flip the lock switch from the drivers side it just buzzes and tries to move to the locked position, but then it flips back to unlock. Now from the outside I can not lock the door with my key. It seems as though the cylinder will not turn to lock it. I can turn the cylinder and unlock it. Has anyone had similar trouble? Can it be a rod linkage inside of the door. I just took my inside door panel off at lunch and hope to work on it more tonight.

Thanks,
David

[epreble]

Have a similar problem, did you get it fixed? Key works from the outside, manual door lock works. Removing the panel shows the key cylinder rod works, manual rod works, but no movement/action when using the electric lock from either side. Electric lock on passenger side and driver's side will work the driver lock. The manual rod tries to lock (slight movement) when using the electric lock, but I do not see anything blocking the manual lock rod from moving and locking the door.
If it is the actuator - how does one replace it?