As a kid I acquired what I remember as a Farrand player piano.  There
was a metal tag on the air motor that advised using only lard or suet
to lubricate the motor.  I don't recall whether the lard was for the
bearings or for the slide valves.

After learning a little about valve efficiency from David Saul, writing
in AMICA Technicalities, I realized that that maker of the Farrand
action had fairly good design.  The valves were suspended vertically.
The moving part of the valve was suspended on a small wood piece perhaps
an inch long; on the opposite end of wood piece had two protruding tiny
sharp pins that were clamped in by a brass clip.  The valve was free to
swing horizontally and friction was very low.  This overcame the
concern about the weight of a valve.

Curiously this same pivot arrangement of using pins clamped by an
indented brass holder was found in the hammer "hinge" of a 1830 piano
I restored.

The Farrand player action worked well.  The top valve (outer) was
simply a brass tube fit into wood.  Adjustment was a matter of sliding
the brass in or out to the proper valve clearance.

Bill Chapman - 80 degrees today in La Quinta, California