Hi Roger,  There is an excellent treatise on Standard Action Co. valves
in the Player Piano Co. catalog:

    Player Piano Co.
    704 East Douglas
    Wichita, Kansas 67202 USA
    tel. (316) 263-3241

Professionally speaking, I endeavor to replicate every aspect of the
original assembly.  By doing that, the worse that can happen is that
the unit will work as good or better than it did when it came off the
assembly line 75 years ago.

Pneumatically Correct,¶
John A. Tuttle (johntuttle@playercare.com)¶
tel. (316) 263-3241