It is my recollection the Hardman Duo made in the 1950's did not have
plastic valves as in later pianos.  When the change was made to the
plastic valves the name was changed to DuoArt, Musette (a full keyboard
39-inch drop-action player), Pianola, etc., and the piano was factory
electrified, although some of the earlier 65-note Pianolas were pump
only.  The stack was moved to under the keybed.

The Hardman Duo was Aeolian's first reissue of a player in many years.
I think it was made in The Bronx, and it contained a Standard-like
wooden action.  The stack was located on top of the keys and was
two-tier.  The lower tier had fingers attached directly to the striker
pneumatics that went under the wippins, the top tier had fingers
attached to a wire loop that attached to the pneumatic.  The pouches
were in a pouch board, the valves (very Standard-like) were in the
valve boards.  The whole thing was screwed together with cork gaskets
and shellac was used to seal around the valves.  This sometimes
crumbles and pieces fall in the valves and freeze them.

I have overhauled a bunch, sanding off the cork gaskets and replacing
them, cleaned the valves and resealed, etc.  The motor is good old
Standard, and the tracker the same, decent sized exhausters and
reservoir -- all easily rebuildable.  A real fun project and they
played rather nicely.

Arthur Marino