bobbling hammers on Yamaha upright (P-22)

[Sspeev@aol.com]

---------------------- multipart/alternative attachment
  Hello everyone. This is my first post, so please excuse any idiomatic 
slip-ups on my part. 

Just recently I began learning how to tune, regulate, and repair (by way of 
apprenticeship).  Before any of this, though, I'd been aware of some bubbling 
notes on my yamaha p-22.  And so recently i set out to correct the problem, 
which pervades the mid-range of the keyboard.  Here's what I did: 

--closed up the hammer-travel distance to 1 3/4" (from 1 7/8").   
--removed the thinner front rail paper punchings (making the key dip about 
7/16") 
--taken out lost motion
--regulated aftertouch so that jack just clears hammer butt

Also--and this was a few weeks back, before dealing with the bobbling 
hammers--I regulated the let-off so that the jack tripped when the hammer was within 
3/8" from string. In retrospect, i wonder if this served to exacerbate the 
pre-existing problem.  Anyway,  the bobbling is not always readily apparent.  
Sometimes you can only feel it (and not hear it) during aftertouch.  Regardless, 
it's making the touch feel weird, and pianissimo nearly impossible.  

One last thing:  many of the keys seem to have a lot of friction to them.  I 
don't know whether this tightness has to do with the front rail or balance 
rail bushings.  Either way, it's quite difficult to remove any given key from out 
of its pins.  
Does anyone think, then, that this whole thing could be friction-related?


Comments much appreciated...  

thank you,
Scott 

---------------------- multipart/alternative attachment
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/2e/1c/10/01/attachment.htm

---------------------- multipart/alternative attachment--