In Digest 970611 Andy Struble wrote:

> It is a late '20's vacuum piano for a large Wurlitzer organ. The valves
> on the stack control 4 pneumatics each and are made of pot metal.  At
> this stage in the game the valves are tight and work quite well; how-
> ever, since pot metal is cursed with its own eminent self destruction ...

Andy,  In my meager experience, if the pot metal in the valves is good
now, it will probably stay good for the foreseeable future.  Pot metal
(basically a zinc alloy used in casting) may or may not disintegrate and
it is usually thought to be a result of some unspecified impurities in
the alloy.

While the manufacturers were not necessarily careless in their processes,
nonetheless, some batches seemed to harbor these impurities and some did
not. Your Wurlitzer castings are now 70 to 80 years old. The ones that
are going to explode will already be starting to do that.

I redid a Wurlitzer player piano a number of years ago and of the 22
casting sets, 5 were deteriorating. The remaining ones were perfect and
I would expect them to stay that way. This particular piano used zephyr
skin pouches and those did deteriorate. I would suggest rebuilding the
valves you have using normal procedures.

Be careful screwing the pot metal parts together so as not to stress
the parts or to break of any of the ears with the screw holes. Otherwise,
use what you have.  The parts obviously could be reproduced with modern
aluminum castings but the number of machines needing them is small enough
that I don't think anyone has ever done this.

If you need one or two parts, let the MMD list know and maybe someone has
a spare or two. Hope this helps.

Bob Conant