1987 560SL Power Door Lock

[JohnC]

The power door lock on the driver's side of our 560SL operates when the key is turned on the passenger side, and also works when the lock is manually pressed in on the passenger side. However, when the key is turned on the driver's side, the power lock does not activate on either door. Likewise, when the lock is pressed in manually on the drivers side. I am guessing there is a loose connection or switch failure. Questions for this group (from a pretty limited mechanic)

-how do I access the inside of the door?
-anyone know if there is a part that can be replaced without installing a new lock and motor?

Thanks!