For Jim Heyworth: see if your piano technician will even the weights on
the keys.  If it takes 50 grams to activate the high treble hammers and
the same amount to move great C, then you might be closer to having the
action more evenly responsive.

While the striking point of the pneumatic are not the same as your
finger, it all still is mass to be moved by the pneumatic.

John McClelland