Hi Jeff,

I never fully got to the bottom of this to be honest - I suspect the lock motor/mechanism is gone in the drivers door (this is also what a series of mechanics have suggested over the years too).
I just got used to simply using the key in the door to lock/unlock the car as a new lock mechanism plus the labour to have someone look at it was going to be too much.
Sorry I can't give you any more info than that - best of luck with it!