[pianotech] Question about perfect pitch

[Bruce Browning - The Piano Tuner]

list,
I have seen several instances where an open faced pinblock has not
withstood the force of pitch raising. Particularly I am referring to
Richard Lipp & Sohn upright. Raising the pitch caused the pins, over a
period of about 2 years, to be ripped downwards, tearing the pinblock
along the grain. On initial inspection the pinblock appeared to be
perfectly able to withstand a pitch raise.
Bruce Browning
The Piano Tuner.