Knocking keyframe

[ATodd@UH.EDU]

   A week or so ago, I posted (I thought) a question to the list but so far
have received no response.
   My question was about a problem I'm having with our Hamburg D. A knock
develops, periodically, in the low bass end of the keyframe. The last time
was an hour or so before a recital. Am I correct that Steinways use a "pinch"
system on the cheek block to keyframe fit? It should press down on the pin
in the keyframe?
   Assuming that is correct, ours does not. This last time I turned up the
glide bolts off the keybed and it still knocked, so I know they are not
holding the keyframe off the keybed. I even swaped out the guides in the
cheek blocks to see if, maybe, the bass end one was worn. It made no
difference. I also discovered some business card type of shims on top of the
guides, supposedly an attempt to lower the guide.
   Can someone offer me correct "fix" for the problem. Unless the guides are
worn, the only thing I can think of is to plug and rebore the screw holes
for the guide plate slightly lower.
   Before the above-mentioned recital I did a fix born of desperation, but it
worked and so far, is still working. With some contact cement I glued a
thin, narrow piece of veneer onto the guide pin in the action frame. It
worked. The action shifts easily and no noise.
   The fact that this did work seems to reinforce the idea that the guide
plates are worn or in the wrong place.
   Any help would be greatly appreciated.

Avery Todd
University of Houston
atodd@uh.edu