This is probably completely unrelated, but perhaps not.

I had this problem with a 1983 SD. The black insert was warn where it hit the latch in the door. This insert is in the catch, attached to the pillar.

It hit on one side (top or bottom, I don't remember), and all the doors showed this pattern. I took the catch off of the driver door and off of the rear passenger-side door, dismantled them and swapped the inserts. Now the worn areas aren't hit by the latches, and both doors work great.

The door catches were different across the car (left and right), but the rubber inserts were identical, other than the wear pattern.