The arm-rests of the frontseats were a little bit loose and procuced noise.

The FAQ of the VW-Bus-Forum shows how to fix the arm-rests.

The easy part is to get the cotter bolt out and loosen the arm-rest to see the two screws and tighten them.

In a second step the cutter bolt has to be inserted again. A simple trick: screw the armrest in a position like on the picture, laying on the seat. Then it will not move too much when you try to get the cutter bolt in again.

Two pictures: