May I respond to two correspondents on the leather for bellows debate?
I agree totally with David Evans that the restorer should always use
the original materials when rebuilding.  I have always said this in
print.

I never said that the ungusseted corners of leather bellows are prone
to leakage.  What I said was that these corners would be potentially
more leak prone.  The comparison was being made to the gusseted areas
of the bellows.  Of course, if one uses the correct leather there will
be insignificant leakage.  The second thickness of leather at the
corners, that David describes, can also help to prevent the leather
from peeling away from the gusset as it can be glued to the inside of
the gusset.

In response to John Tuttle's comment that he has never seen a reproducing
or expression piano with a leather rotary pump, may I refer him to the
Popper's Welte Konzertist?  I am currently rebuilding one of these.

This is a German electric cafe piano which contains a sophisticated
expression system, but is not quite a reproducer.  It has a large box
pump where each of the four feeders is covered with thick leather and
is also gusseted, in spite of it being a suction system.  This supports
an earlier correspondent's comments that suction leather feeders should
be gusseted in order to prevent the leather flapping at the change of
direction.  Even after 80 years, the leather is still in excellent
condition.

Interestingly, the equaliser is covered with rubber cloth, presumably
as it isn't as 'lively' as the feeders.

Best wishes to all,
Nicholas Simons, England