The serial number of the Franklin piano is 93088, which puts it about
1922.  It was always a foot-powered player.  When I acquired it, the
valve assembly for the bass side expression unit was missing, as was
the hammer rail pneumatic.  I just duplicated the expression valve box
from the treble end and created a hammer rail lift pneumatic that
mounted and worked the way it appeared to have been built originally
(from the remaining screw holes and other hardware).

Except for the pedal assembly and the inverted pumping bellows, the
construction of the exhausters unit is very much Standard Pneumatic
Action Company.  The same is true for the action stack and tracker.
The hinge end of the pumping bellows even had the reinforcement rope!

The references I am seeking have specifically mentioned many of the
special features in this piano.  These include:

 - getting rid of the air motor:  This instrument has an early
Melville Clark spring motor drive.

 - doing away with the troublesome "L-board":  Between the primary
and secondary valves there are elbows and rubber tubing.

 - providing a "self centering tracker":  On top of the spool box is
a clever little spring centering mechanism in the tracker linkage.

There are many other significant features, but these are the ones
I remember having seen reference to in various articles.

Thanks for your help and interest.

Bob Hunt