124 1994 e320 door locks

[mcdill]

I have a problem with my central locking system that seems very strange. Starting with the outside locks (using the key)...unlocking and locking from the driver's door works fine. Unlocking and locking from the passenger door or the trunk will activate all locks except for the driver's lock. Only on rare occasion, once or twice a month, will the driver or passenger lock activate the driver's lock as well.

From inside the car, the driver's door does not unlock any of the other doors, unless the car is on. With the car on, the entire system works fine. So, when I turn off the car and open the drivers door from the inside, only the driver's door unlocks.

From doing a search, it sounds as if something is wrong with the driver's side vacuum. I know on the 123s that there is a diaphram in each door...not sure about the 124. What would I need to replace in order to get the system working properly?

Thanks in advance.
Matt