I noticed that in my 1926 Ampico A Mason & Hamlin there is a curious
restriction added to the right-side-up valve.  On the top of each
valve there is an overlay of a leatherette disc glued on top of the
metal.  It has a hole in it that is smaller than the ordinary hole.
It is about 1/8th inch opening, which would restrict air flow, and
possibly alter (?) the atmospheric pressure pressing on the moving
part of the valve itself.  I have found nothing in the literature
about this little disk.  I have pictures if anyone is interested.

Is anyone producing the metal top or other parts for the Ampico A
valve?  Opening up the unit valve is going to be a bit risky.
Pouches are getting leaky and non-uniform.

Bill Chapman
shazam32@earthlink.net.geentroep