With a home-made manometer I just determined that my LP pressure is over 30"
of water.  That was the limit of my instrument as when I connected it to the
line, it immediately blew all the colored water out the top.  My regulator
is marked "Model 290-01" (definitely not 260).  This regulator came with a
tank I got from GoWesty 2003, so I presume it is a modern two-stage
regulator.  I'm trying to figure out how to adjust it.  I took off the
plastic cap and see a large plastic dial with a kind of indicator, but it
doesn't budge by hand, and I can't think of a tool that would turn it
safely.  I'm not convinced it's designed to turn.

Can anyone advise?

This, incidentally, was professionally installed in 2003, and I explicitely
asked them to make sure to adjust it to 11" of pressure.  Don't know if they
ignored that, or if it has somehow gotten out of adjustment since then.

Could this excessively high pressure explain my refrigerator not cooling
adequately on LP, when it works ok on AC?  I've tried everything else I can
think of to solve that problem.

Thanks, all.

Paul