Gribble Piano Co. of Kansas City was mentioned a few days ago in MMD.
They did make a player in the late 1950's.  The one I'm thinking of
was an electric-driven 88-note pneumatic player called "Magic Fingers."
It consisted of a drawer under the keyboard to carry the spool box and
a single-row pneumatic stack attached to be bottom side of the keybed.

The little striking pneumatics were connected to the bottom of the keys
at the front end and pulled them down via a strap similar to a bridal
strap.  Gribble claimed this gave the machine a "human touch", as it
acted on the same end of the key and directly below the ivories where
a human would play it.

The pump, at first a turbine and later a small box four-bellows pump,
set beside the piano with an electric cord and a vacuum hose running to
the piano.  The machine played nicely when new, but with no expression,
of course.

After this amount of time, I'm not sure of the following, but I think
it had an automatic sustain pedal, a knob that allowed the volume to
be set within a range from "background-soft" to medium loud, plus
automatic reroll and cut-off.

I believe all of the Magic Finger units I saw were factory installed
in spinet pianos.  I think the device was supposed to be installable in
any piano, grand or vertical, as a kit.  They weren't around very long,
and I've never seen or heard of one since.

My impression was that the Gribble folks went to some effort to put out
a well-built quality unit, but I have no idea how well they held up.

Regards,

Dick Merchant
Carlsbad NM