I have a barely-functional player piano, and I was hoping someone here could point me in the right direction. It is from around 1912, and is manually operated (i.e. no electric pump).

The biggest problem (currently) is that the roll will sometimes stop advancing. When pumping the pedals, I can feel suction build up, and it feels like a valve or something will suddenly stick, preventing the roll from advancing further.

When I then *stop* pumping the pedals, I can audibly hear the suction start to go back down. After several seconds, the valve (or whatever it is) unsticks, and I can start pumping the foot pedals again, and the roll will play some more.

But whenever too much suction builds up, this sticking problem occurs.

Can anyone tell me what mechanism needs adjustment?

Thanks in advance.