I read Kirk Gibson's note today about starting to rebuild his Duo-Art
player action stack.  My first reaction was a shudder that ran up and
down my spine.  With all due respect to amateurs, tackling a Duo-Art
is above and beyond the ability of most amateurs.  I would recommend
breaking in your teeth on a more simple mechanism first to build the
necessary skills.

1. Replace the gaskets with pouch leather gaskets.  If you are the next
one to tear the stack apart, you will be glad that you did.  I don't
one to tear the stack apart, you will be glad that you did.  I don't
know how cheesecloth works here, but the pouch-leather gaskets that
Aeolian used are exceptional for a rebuilder.

If the stack pneumatics look fine then you probably need glasses.
Either this or it was rebuilt at a later date.  Many pianos were
rebuilt by replacing only the stack pneumatics; this was a while ago
when we could still count on the old leather.  It's a puzzle as you
said that the tubing was as brittle as a pretzel.

Read Art Reblitz's book for pouch dipping.  His technique is clear
and correct.  If you need a dipping tool, I improvised one by taking
Dremel tools: a large disc first followed by smaller discs made a
lovely dipping tool with very little investment.

While you're at it replacing the pouch leather, don't forget the valve
leather as well.

Before you reassemble it all, check each piece to make sure it's
air-tight.  You should be able to suck on the stack at it's joining
point and not breathe in any air (it must be perfect for the Duo-Art
to perform).

Good luck,
Eli Shahar