Hi Dave,  Pandora and I just finished rebuilding a Hardman Duo stack.
Without exaggeration, it was a mini nightmare.  The biggest problem _was_
removing the pneumatics.  I tried every trick in the book, including
heat.  Fortunately, I had a few block value units to replace the ones
which were destroyed by the heat traveling down the air channel from the
pneumatic.  I finally resorted to brute force and a chisel.

One mistake I did make was scoring the edges of the pneumatics to break
away the excessive glue.  The tiers are made with a thin plywood face
that (in my case) came away with the pneumatics in a few cases due to the
cuts I made.  The wood that the pneumatics are made of is very cheap and
poorly chosen with regards to the grain.  Over one-third of the boards
that mount to the stack split or broke irregularly and some of the
language in the shop got pretty colorful.  I'm a very patient rebuilder
but I was very frustrated by the time the last board was removed.

I have already decided to change my approach to these units in the future
and completely avoid the nightmare by making new bottom boards from the
beginning.  That way, I will be able to strip off the upper board and the
hinge material and get tough with the lower boards.  Then plane off the
remnants of the bottom boards.  You might ask, why didn't I do that
initially?  When I started removing the pneumatics in the standard
fashion, the first 20 or so came off pretty cleanly.  Then things slowly
got worse.  By the time I had finished the second tier, things started
getting messy.  And through most of the last tier, things were awful.

The problem that caused me to reconsider my initial approach in the
future had to do with the thin ply to which the pneumatics are mounted.
The ply pulled away from the base wood and allowed air to seep between
notes.  Since I could see it coming, I took appropriate measures to
insure an air tight seal between notes but it was extra work that could
have been avoided.

In closing, I know that there are going to be many of these units that
will need rebuilding over the next ten years because they are reaching
the end of their usable life.  I have, therefore, already decided to
raise my price for this job by 25%.

Musically,

John A. Tuttle "Self-Playing Pianos"    http://www.PlayerCare.com
407 19th Avenue             Pri E-Mail: JohnTuttle@PlayerCare.com
Bricktown, NJ 08724      Secondary E-mail:tuttleja@concentric.net
"We Keep Your Music Rolling"     Authorized QRS Music Roll Dealer

 [ John, thanks once again for sharing your experiences in MMD.
 [ Your patience (Pandora's, too) deserves an award !  -- Robbie