I just rebuilt my first Concert Roller Organ about one month ago.
I had to replace all of the pneumatic cloth and valves.  The organ
seemed to be original and never rebuilt.

What surprised me was that the vacuum reservoir valve flaps were
covered using pneumatic cloth, rather than leather.  The internal valve
flaps were also covered with only the pneumatic cloth.   Was this a
common practice with these organs?

To make new valve flaps, I glued leather to new pneumatic cloth using
hide glue.  The four new flaps were then tacked to the boards with small
tacks, just as it was originally done.

When everything was assembled I had problems with the pump folds
popping out when playing.  I removed the cloth from the pump bellows
and put reinforcing gussets on the inside of the cloth and then
re-glued the pump cloth.   This solved the problem.

In looking back, I think that the original problem might have been that
I stretched the new leather flap material too tightly over the holes.
This would cause undue positive pressure inside the pump bellows when
exhausting the air.  What do you think?

Pete Knobloch (Tempe AZ)