Hi All,  Just for the record, I've never heard of or seen a rotary
vacuum pump for a reproducing or an expression player system that had
bellows that were covered with leather.

Just thinking about such a vacuum pump, my immediate concern would be
that leather stretches.  Taking the thought a step further, it's even
important to consider the bias of heavy bellows cloth when rebuilding
a rotary pump.  This is because the cloth stretches a bit in one
direction but is very stable 90 degrees to the right or left.

It is because of the above that I now sell "strips" of heavy cloth at
Player-Care.  I found that people were buying lengths of cloth that
were too short for the job.  It became clear to me that they didn't
realize that the cloth would 'self-destruct' when stretched in the
wrong direction.

Musically,

John A. Tuttle
Player-Care.com
Brick, NJ, USA