I did my 82 Mercedes last year. Older vanagons use the same style brake pads - not sure what year the one youre speaking of is...
First, check the brake hoses. Replacement is likely.
Second, verify piston engagement.
My car had a piston on each side (so I guess dual piston calipers).
The FSM called out ATE Plastilub, and showed where to put it.
Personally, I put a bit of copper anti seize on the pins that go through those two ears on the top.
On the MB pads, the shim is essentially built into the back of the pad. I personally did put a very little bit of plastilub on the back of the pad, and some on the rubber seal in the caliper.