Puzzler for a quite Sunday. :-)

[JIMRPT@AOL.COM]

Et Al;
 A few weeks back I had occasion to service a Kawai Grand, don't remember the 
model number, but it was about 6' and aprox a year old and the better line.
Complaint was:
 "There is a clicking noise in this key and in the key on either side but not 
as noticable as in this key" and "the noise only happens sometimes and only 
on the upstroke of the hammer" (The customer was a VERY good player:) (the 
keys were A#4, B4 and C4.)

 I tuned the piano, did a little voicing and then addressed the problem of 
the "clicking" by the judicious use of a 'tiny' bit of felt............
What was the clicking noise?
What did I do to stop the clicking?
Have fun! :-)
Jim Bryant (FL)