David Dewey asked in MMD 141223 about replacing valve facings.  If
things are getting along alright in the valve, well, leave the original
facings in there!  This is especially the case on valves where metal is
used as stems or seats like, say, Standard Pneumatic (stems and seats)
or Aeolian (seats only).

New leather may be more likely to have salt or whatever it is that
makes leather corrode metal in the leather.  Lots of us have seen the
damage caused by leather nuts installed on poppet wires and other
connecting linkages.  Sometimes the nuts are only a few years old and
they start eating away at the wires.

Valves that don't have metal in the equation, like, say, Ampico, are
safer since the leather sits on Bakelite or wood so the salts in the new
leather are less of an issue.  In the case of Simplex that Mr. Dewey
mentions, where you often have to replace the vacuum side leather that
seats on a polished brass ring, try using traditional tan pneumatic
leather as opposed to CPL, as CPL is a "chrome" tanned leather and,
I am told, a salt-cured leather.

Most player actions, like Standard, that leave my shop have the original
vacuum side leather, not because I am lazy but because I believe doing
so is a best practice for longevity.

Ben Gottfried - Ben's Player Piano Service
Richfield Springs, New York
http://www.bensplayerservice.com/