> This
> suggests that the main valve does not close completely. So the whiff of
> propane that I smell from the tank area could be from any part of the
> plumbing.
>
> What's the scoop on those valves? Rebuildable? Available for replacement?
>
> I wonder if a valve that does not close completely could also be the
> leak source.

The "service valve" can wear out.  I replaced mine when I had to
crank harder and harder to have it not leak--just like you report.

Here's what you need (right photo):
http://www.pplmotorhomes.com/parts/lp-gas/propane-refill-adapter.htm

You are also working toward understanding that you need a new fill
valve (left photo) (and bleeder valve), but maybe you are not
there yet....

The web site is for illustration; your local RV dealer might have
better prices.  But do notice how inexpensive a regular fill valve
is--to get rid of the AutoStop.  ;-)

Richard
Boulder