Here are a few more details about my previous posting about making
the keys move.  I agree that rubber bands are not a particularly good
solution.  That is why on my second piano I used a small clamp and loop
of thread to couple the key tail to the whippen.  Here are some details
of that approach.  I am afraid I don't have any photos since my piano
was done many years ago.

On the Duo-Art at each key tail there is a metal rod on which is
threaded a wooden dowel.  This acts as the key capstan.  I fabricated
a little clamp by taking the metal from inside of an ordinary electrical
terminal block and cutting it in half.  I effectively made a little
metal ring with a clamping screw sticking out one side.  I slid this
over the metal rod of the key capstan, after, of course, removing the
threaded wooden dowel.

I now ran a loop of thread over the whippen and the screw sticking out
of the new little clamp.  I adjusted the location of the clamp to just
allow a tiny bit of lost motion between the key and the whippen The
keys now moved as the piano is played.

I hope this makes things a bit clearer.

Phil Dayson