Greg,
As the buckskin and underlying cushion become worn and
compressed, the jack has to pull out farther in order to clear and
allow letoff. And, when key is released, jack will have to travel
this longer distance to get back in position under the hammerbutt.
Jack may drag on leather before hitting rest cushion. Key depth has
to be increased to get adequate aftertouch. Without going into more
detail, we can see that this scenario = mushy letoff, slow jack
return, poor repetition.
(My thanks again to Bill Spurlock's class on upright regulation)
Roland Kaplan
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