Help!  I am trying to help a friend restore an early Ampico.  The
problem is in the old style inverted unit valves.  I have little
experience with this style of unit valve.

The bottom seats are wood, the inverted tops are wood with a metal
ring, glued on with paper shims. The valves have been replaced and
correctly re-gapped. The new pouches are dished properly.  Still, many
of the valves are leaking when the vacuum is directed to the pneumatic
stack.

Can anyone help us with this problem?

Bruce Clark