Piano Mystery

[Bonifield/Poulson]

List Members All: All right, I've got one for you.  Why is it that on 
some uprights the let-off distance increases as the action gets more and 
more out of regulation?  I have observed this phenomenon many times when 
first being called to service a piano. Intuitively it would seem that as 
the let-off puncning wears it gets thinner and allow the jack to trip 
out with the hammer closer and closer to the strings.  This I have seen 
(blocking hammers) but I have also seen pianos with let-off distances at 
1/4 " and more, and the owner swears that the instrument has never been 
regulated in recent memory.  Is it possible that on all these pianos a 
previous technician somewhere in the forgotten past has gone through and 
adjusted let-off wider for some reason?  Or am I a victim of 
tuning-induced delusions?  Patrick Poulson, RPT