My 1987 300D has a peculiar lock problem. The driver's lock only operates the driver's door. The passenger lock & trunk lock will operate all the locks. I tried replacing the driver's door actuator, but that didn't help. I think I can rule out a vacuum problem since the driver's door will lock & unlock from the trunk. I'm wondering if it could be the electric vacuum pump. My rear headrests will not retract either. Could this be tied in with a vacuum pump problem???
1987 300D Turbo 109K mi.