Manchester tank says to not rebyild aluminum auto stop valves.The brass
will take a rebuild.However, A good cleaning will probabley do the job(that
is what I say).2 pieces inside. One is an O-ring that is about 2 inches in
diameter. Manchester wants $20 or $29 for this o-ring. Your old one is
probably still good,unless it is flattened or pinched. I would check it out
before plunking down $30 for an o-ring. Even a gold one. Just disassemble
the valve and clean it. No lubrication!!!  Cant go wrong with only 2 pieces
to worry about.4 nice big phillips head screws hold it all together. If
anyoneis having a  problem with tthe auto stop valve,I hear that it is
necessary to open the valve completely while filling it. Problems arise
when the attendant only opens the valve partially ,and begins to
fill.This,I hear is the reason for the bad reputation.So ,clean it and open
it.You dont ever want a valve to get stuck open .Very scary.Had it happen
once.The propane just comes back out and freezes everything in sight.By
time al;lthe propane is released(propane is a refigerant),you have a block
of ice weighing 20 pounds, frozen to the tank, rocker
panel ,wheel,frame,ect,ect.And a $20 propane bill and a dont come back
again look from the attendant.