I found Jere DeBacker's information very interesting.  Over the many
years I've rebuilt quite a few of these Melville Clark pianos.  Every
single one was different in either a major or minor way.

I always assumed the action that pushed the keys down in the front was
an earlier design; I remember them being associated with an earlier
serial number on the piano.  The cases themselves were made differently
to accommodate this action.

I agree that the leather used for the "pouch pneumatics" inside the
chest was some of the most beautiful leather I've ever seen.  I don't
remember ever having to reseal them.

I did always change one seat to brass or a phenolic type.  It improved
playing by 50% for me.  In fact, the leather button was always in perfect
condition, which is something that always needed replacement in other
actions, even way back when.

I've had two or three Apollophones that had a phono disc player behind
a panel that opened to the left of the spoolbox.  I also remember the
movers groan when they had to move an Apollo.  They always wanted to know
"What's in this thing?"  Jere, I would appreciate knowing any details
that you might compile regarding this player.

My original caveat remains:  Do not open the clutch assembly!

Regards,
Bruce Mercer