Instructive Challenge of the Day

[Conrad Hoffsommer]

At 11:57 3/21/2005, you wrote:
>Upright 1890 Kranich & Bach, in very good condition after much work, had a 
>treble hammer that bobbled a bit.
>
>Checked regulation points, all similar to its neighbors which worked fine. 
>Held the left pedal down a bit; didn't help. Tried the key with fewer 
>front rail punchings; no help.
>
>Realized the hammer wasn't checking at all. Tried adjusting backcheck; 
>hammer would not check in any position! Made double-sure backcheck was 
>aligned squarely to catcher and that felt and leather were good--same as 
>neighboring notes.
>
>Hmmm.
>
>Perfectly squaring and aligning the backcheck was what led to the proper 
>diagnosis (hint) but did not improve checking at all. Repair took a about 
>30 seconds and did not require turning any screws or any regulating. In 
>fact, I used no tools at all. Hammer now checks perfectly, wherever I want 
>to adjust it.
>
>Age of piano is a hint, although the problem had nothing to do with the 
>brand of the piano or it's action design which is very "modern," at least 
>as far as wippens, hammers, and butts go (but don't get me started on it's 
>rocker capstans and short, secondary stickers that are attached with 
>screws to the capstans). The point is, this problem could occur in ANY 
>upright but is more likely in an old one.
>
>No purchase required to enter.
>
>Alan R. Barnard
>Sendin' Out Stumpers From Salem, MO
>


Glazed backstop and check. Used nail file to rough up surfaces?

c