Seems that the checkvalves in my westy "city" water system may be
built-in pressure regulators, but they seem a bit crude for that. At
any rate, the gowesty water inlet has its own check valve, as does
the brass fitting part that came with the original westfalia-supplied
parts. I never had the original westfalia water inlet, so I don't
know if it had a check valve originally.

The gowesty aftermarket part has a rubber ball and a spring. After
some digging around with a chopstick, I got it loose and rotated the
ball so the "dented" side, if there was one, would no longer be the
seating side.

Put that back together and now it allows water to the faucet. Turns
out I spoke prematurely when I pronounced it OK. It wants to work
either for the T or the C position, but not both. This is due to a
crack in the underside of the knob, and I am attempting to fix that
with my newly-acquired tube of super-duper plastic repair system that
I used to fix the cupholder with last week.

We'll see.

Jim