Adrian Schmidt wrote:

> But is there a system that can control the keyframe or
> tracker bar?

Dear Adrian,

I manufacture the PowerRoll digital converter for pneumatic player
pianos.  It is definitely possible to make a unit which will actuate
the fingers on a keyframe and be adjustable to different scales, if
there were sufficient interest to justify the effort.  We can also
build a pressure-model Tracker Bar Interface.

If the keyframe is tubed with rubber, I can provide a pressure-control
unit which will tee into your keyframe tubing and, in turn, be
efficiently and accurately controlled by an inline-model PowerRoll.
I would not recommend disturbing original metal or other hard tubing,
however.

Please let me know if you are interested.

Best wishes,

Larry Broadmoore
http:/www.erolls.com/   for PowerRoll information.