You said:

<dealer did the following:

new fuel filter (Bosch)
checked brakes (70% remaining on all original brakes)
checked engine compression (155/155/155/155)
topped up transmission/front diff fuids
checked steering/suspension
inspected exhaust (all original)
adjusted ignition timing
checked ECU fault codes
checked emissions control systems
tested catalytic converter efficiency
adjusted engine basics
installed new Bosch oxygen sensor (I supplied part) (30 min. labour)
inspected belts (tightened a/c belt)>

You did (and had done) all of this and didn't REPLACE your belts?
I think that's a false economy.
Them belts will get you every time!

Just my $0.02.

Sam Bateman
'87 Vanagon GL