Got the core removed from the plastic blower casing this morning, and
cleaned it up.  Lots of dust and what looks like dog hair in it, but
otherwise looked pretty good.

I rigged up a couple of pieces of heater hose to my air compressor and
pressurized the core to 20 PSI and dunked it in a bucket of water.  No
bubbles from the core itself, but there is significant leakage from
the valve "O-ring" if even slight sideways pressure is applied to the
valve housing.  So I think I've found my problem.

Are new O-rings available?  Or do most folks just augment the O-ring
with some RTV?

Allan
--
1991 Vanagon GL