Steinway, Model M Grand knocking rattle noise

[JIMRPT@AOL.COM]

Arthur;
 You have gotten several good replies. A thought that is nagging at me, given 
the symptoms, is that possibly the wire flange is bumping the upstop rail. 
Given the underlever geometry of that model 'M', and the loose guide rail 
bushings, the combination might be more than enough to cause this to be your 
problem.  If such proves to be the case....... rebushing is called for along 
with possibly some judicious wire bending, at least on the problem notes.
 If not ,then ignore the previous misopinion :-)
Jim Bryant (FL)