[pianotech] Clicking noise in Acrosonic

[John Formsma]

Wish I could post this as a solved "puzzler", but I'm still puzzled.

1980 Baldwin Acrosonic. First visit 2-3 weeks ago did a pitch raise and
tuning. Pointed out to the owner the clicking noises that were ostensibly
due to the deteriorating grommets. At least that's exactly what it sounded
like, and they were deteriorating/ed. Replaced the grommets today, but there
is still noisy clicking in a number of keys. And it sounds rather like the
click that comes from deteriorated grommets.

Observations:
The noise only happens when the key is struck at a mezzoforte - forte blow.
Pianissimo and piano produces no click, and neither does fortissimo. I could
not make the noise when moving the wippen/hammer by hand (from below the
keybed). But as soon as I struck the key stick, the noise was produced on
string impact (or so it sounds). It sounds like the clicking from bad
grommets, although the noise is coming from the action and not the key
(placed a firm hand on the sticker itself and struck the key, and the noise
was still there).

All the usual suspects were eliminated, so I'm stumped ... unless it's
Corfam. (Which I haven't yet dealt with. Archives seem to be down, so
searching now isn't possible.)

Does Corfam cause clicking sounds? I moved the backcheck back to eliminate
that as a possibility, but obviously cannot remove the jack from the
equation.There was no noticeable click when forcing the hammer back to its
rest rail (in an attempt to make the hammer butt click on the jack, if that
is what is happening). Both hammer butt and catcher surfaces are rock hard.
It used to look like leather, apparently ... there is a leatherish, ecsaine
tint there ... behind the aged look.

It is not:


   - bad hammer shank/head glue joints (was mfg with those "half shanks" in
   the butt end. Shank replacement seemed to correct one at first, but it came
   back later, and shank replacement in another made no difference.)
   - loose damper heads (tightened)
   - loose action screws (all tightened prior to grommet replacement)
   - excessively loose pinning (8-9 swings, and the flange held up its
   weight, and moved slowly with the weight of the screw)
   - loose key top
   - loose fork at the end of the key stick
   - key bushings, although there is wear, I replaced one with no difference
   in the noise.

Did I miss anything, other than replacing the hammer butt and catcher
leather?

The owner is a nice lady who sat in there with me during the whole
procedure. We were able to talk most of the time, which was nice. I told her
I was stumped, and they are OK with that. They are not asking for
perfection. However, the grommet replacement that *I recommended* was
supposed to stop the clicking, and I'd like to see it fixed. I'm not willing
to do an entire Corfam replacement for free should that be the solution. But
I could replace the worst (about 10-15), and feel like I held up my end of
the deal.

Thanks in advance.

-- 
JF
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