Dead note puzzler: grand key moves, hammer doesn't

[Andrew and Rebeca Anderson]

Greg,
Sounds a lot like a capsizing action to me but with a new twist, a 
key that moves freely.  I've got a D doing this but the problem 
involves weakened rep. springs to accommodate poor checking as a 
result of severely arcked and roughened hammer tails that barely 
reach and tear up the checks.  Some much-needed hammer filing sure 
didn't help!  I can't regulate this as close as I'd like to.
I'll have to keep that screw-spoon interaction in mind for when I encounter it

Thanks,
Andrew
.
At 11:26 PM 6/4/2006, you wrote:
>A customer with a nicely rebuilt Steinway "B" called
>and asked me to fix a "dead" note.  He said the key
>moves up and down, but feels light.  The hammer does
>not move, and is slightly lower than the others.
>
>I arrive a few days later, and the note in question
>(G#6) now functions normally.
>
>The hammer flange pinning was tight in most of octave
>6 (one or two swings, which I fixed), but even if the
>flange was frozen, that would have locked the hammer
>up at the string, not down on the rest felt.
>
>The wippen was slightly misaligned toward the G6
>wippen, very close, but not rubbing.  I fixed that.
>But even if the wippens were catching on each other,
>it seems like that would have locked the hammer up,
>not down.
>
>I played the note repeatedly, scales, chords, etc.  No
>problem.  I figured I fixed it, though didn't know
>how.  Started tuning, worked up to G#6 and gave it a
>good test blow.  It went "dead" again.  Just as the
>customer had described.  I pulled the action and
>removed the wippen, and the cause was obvious.  WHAT
>WAS IT?
>
>Hints:  It was not a foreign object jamming the works.
>  The wippen was not unglued or otherwise broken in any
>way.  This probably would never have happened on
>anything but the newer style wippens.
>
>I'm about to give you the answer, so stop reading if
>you want to figure it out yourself.
>
>See the attached drawing from the Renner catalog.  The
>wippen has the handy new adjustment screw for the
>repetition spring.  The screw on this note was run
>down several turns more than others on the piano.  The
>plastic spring-bearing on the bottom of the screw was
>catching on the jack regulating spoon after a very
>hard blow.  The hammer was checking very low.  The rep
>lever was being pushed down too far by the knuckle and
>sticking.  The jack could not return, but the hammer,
>wippen, and key dropped back down, with the shank
>resting on the cushion, and the jack against the
>proximal side of the knuckle.
>
>Fix:  Adjust backcheck for proper increasing
>resistance and checking distance.  Back off rep spring
>screw and increase spring strength the old way. Bend
>the jack regulating spoon slightly, and then realign
>the jack with knuckle core.
>
>Test:  Much like testing for backcheck clearance, push
>down on the key and hammer at the same time.  After
>letoff, see if you can push the hammer down on the rep
>lever far enough to make the lever stick.
>
>That was a first for me.  Maybe everyone else has
>already been there and done that.
>
>Greg Graham
>Brodheadsville, PA
>
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