According to the recent Pianola Institute concert in London, of
the 3-roll "Primo"-only set created by Rachmaninoff, only the Second
Movement is presently known.  It has had very limited use over the
years, and I don't believe it has ever been made generally available.
For the Pianola Institute concert the original roll was scanned and
copied in a form with Duo-Art coding, so clearly there is some degree
of availability of the material.

The accompaniment came from Rex Lawson using the Themodist 88-note roll
version of the concerto.  Given Rachmaninoff's free interpretation,
keeping the accompaniment in line with his roll is difficult:
apparently when played with an orchestra some years ago the two were
about a whole bar apart at times!

My late friend, Sid O'Connell, spent a great deal of effort in making
a piano-solo MIDI version created from Rachmaninoff's 78 recording, and
this was used from time to time at Hurstwood Farm with its Boesendorfer
SE playing solo with the original 78 recording playing: the timing was
good enough that the original piano sound was wholly masked.

Julian Dyer
Wokingham, Berkshire, UK