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Hi,  I recently bought a Weber Half Duo-Art (foot-pumped) pianola
piano after looking for one for some time.  It will play standard rolls
okay (pumping is a bit hard), but the Duo-art mechanism does not work.
It is my plan to re-build the whole player action.  There is one
expression box and one accordion pneumatic only.  I have read earlier
postings on how half duo-arts work, but must confess, I am still
confused.

There are four main valves with tubes on the expression box.  One tube
goes from the bass half of the box, another from the treble.  The other
two tubes; one goes from the bass and one from the treble, but these
two are joined.  The tubes were all off the junction box at the top
when I got the piano so I have no idea where they are meant to go to.

Could someone outline the workings of the half Duo-art system, and
what the piano actually is supposed to do when it plays a Duo-Art roll?
Also, what is the difference between a half Duo-Art playing a Duo-Art
roll and playing a Themodist roll?  Hope I have not totally confused
everyone!

Thanks for your help all,
Jason Fisher