Hello MMD.  On page 175 of his book, "Player Piano, Servicing
and Rebuilding", Art Reblitz mentions that breaking open the
Duo-Art expression box is the most difficult part of a restoration.
He also says that this operation is described in the rebuilding
guide by Mike Kitner.

I have the expression box out of my Steck Half Duo-Art sitting
on the bench at the moment, and it's looking at me quite
aggressively.  I would very much like to know where I can get
a copy of the Kitner guide.

John Phillips in Hobart, Tasmania

 [ D.L. Bullock wrote a good technical article about this, see
 [ http://www.thepianoworld.com/technical_tips/duo_art_expression_box.htm
 [ -- Robbie