So, on to my next attempt at fixing what seems like a never ending list of problems. As soon as I solve one, another pops up.

I've got a 87 300SDL. If I get another one of these cars, I'm going to go older and avoid anything "auto."

When i unlock my car, all four door locks go up. When I lock it, only three go down. The rear driver's side lock wont drop. I have to push it down in order to lock it (goes down pretty easy).

Since it goes up (an all the others work fine), I'm guessing it's not a vacuum issue. Would I be wrong in this assumption.

Any ideas on where to start?