Jumpy tuning pins

[Alan Rudolph Zajicek]

Hello all,

I just tuned an old M+H BB that had been restrung sometime in the past
(10-20 years?) with either fat no.3 pins or skinny no.4's.  Upon initial
inspection the previous tuning- done last Jan. by some one down state
before the piano was moved here (chicago)- was remarkably solid.  The
piano was about 4 cents flat so I thought "piece of cake" tuning.  As
soon as I touched the first pin and thought "How nice and tight!", BOINNNGGG!
jumpy pins!  The whole tuning took 2 1/2 hours fighting strings that went
either way sharp or flat of my aim.  I had to get each note close to
pitch and then use my hammer to knock the pin fore or aft to "fine"
tune.  The wire itself rendered quite nicely across all bearing points
and the final tuning was certainly acceptable and musical, but what a lot
of work!  Exactly what causes jumpy pins and what if anything besides a
new pinblock will cure this problem?  I would say that 80% of the pins
were jumpy, 15% marginal, and 5% OK.

Best to all,

Al Zajicek RPT