I once bought a Steinway Duo-Art grand, which worked very well when
I looked at it in the seller's home. It seemed to be a okay rebuilding
job from 15-20 years ago.  The interesting thing was it stopped working
after I moved it, due to valve leakage.  I came to the conclusion that
during the move several valves had rotated and the cross-shaped
impression in the leather was no longer in the cross-shaped valve cap
hole.  I have serviced older Aeolian rebuildings and noticed when I did
have problems with leaky valves the vast majority of the time they were
cross valves.

I believe, after disassembling the stack, the type of leather used by
this rebuilder was at least as much to blame as the original cross
valve design was for this major valve leakage.  The original Aeolian
leather was dense and the nap seemed good for the cross valve design.
The leather Aeolian used was resistant to compression and leakage.

Unfortunately, I don't know where to get leather like Aeolian used "back
in the day".  I considered using patent leather but didn't want to take
a chance, I was so unsure about how the leather I used was going to
fare ten to fifteen years down the road if I were to leave the cross
valves in.  I figured Aeolian must have changed the design from cross
valves to round caps for a good reason.  I did the conversion to round
caps reluctantly.

Bill Maguire