Attached are two photos of the Duo-Art fan system I'm particularly
looking for.  They were apparently designed for the above keyboard
"drawer" models.  Those are the ones that have spoolbox, stack and
expression box in a sliding drawer, all above the keyboard.  Note
they have leaf springs but no wound coils springs (saves space).

Presently I know of several complete pianos with this system, and
several units on parts shelves, accounting for six of this model.
The earliest piano with one of these seems to have been built in 1928.
Development would have to have taken place probably in 1926 or 1927.

My guess is there are more.  They do not take long-play (Jumbo) rolls;
so far as I have seen, though, I would not be surprised to see one of
the jumbo top-action spool-boxes fitted into one of these above
keyboard drawers.

I would like to beg, borrow, rent one of these expression boxes that
only has leaf springs for a month.  Would buy, if necessary.  Would
also like to buy a Duo-Art transposing tracker bar.

 [ See the photos at the MMD Tech site, under the category "Duo-Art",
 [ at http://mmd.foxtail.com/Tech/  -- Robbie

Bruce Grimes