Student Question - Read only if in magnanamous mood.

[Benjamin Treuhaft]

p.s. John,  When you finish shaping  and spacing, push each hammer up
against its unison from the catcher and pluck each string to make sure
each is deadened by contact with the hammer (have your foot on the
damper pedal).  If not, correct the shape of the hammer or push the
high string or strings down into the plate near the nut (upper bridge)
until they are all deadened.  Gets rid of awful zingy noises.  Same on
a grand, but there's a trick to it that's hard to explain online.
Ben Treuhaft (Senda Piana to Havana)
Berkeley, Calif.