[pianotech] wooden click at letoff?

[Jon Page]

Since it is in the shank/flange, look for a loose rep lever upstop 
(drop) screw, a drop of CA fixes that.

Other sources of noise at let off:
A hard cushion at the end of the rep lever, under cut with a 
narrowed-down Exacto blade.
  This releases the hard bond and reduces noise upon upstop screw contact.
The end of the rep spring is binding within the jack.

-- 
Regards,

Jon Page