Buzz in an S&S D

[Andrew and Rebeca Anderson]

I did a pre-concert-rehearsal tuning on an S&S D at a local venue 
today.  There was a pronounced buzz for notes B3 B4 B5 when firmly 
played.  I have already treated a cross-strut buzz on this piano 
successfully.  Checking it did not change the buzz at all.  I put my 
hand down through the second hole on the plate and pushed on the 
sound-board which stopped the buzz.  ?!!  This is a five-year-old D 
with a DC system on it which until I came three years ago wasn't 
plugged in much.  It is on constantly now and rarely deviates by much 
in tuning or regulation.  I'm guessing rib/rim separation.  Does 
anyone have other ideas to pursue.  I felt around for foreign objects 
contacting the board and didn't encounter any.

I'll be going back for the pre-concert tuning Sunday morning armed 
with a bright light, syringe with needle, and CA glue.  I'm open to 
other ideas.

Andrew Anderson, Artisan Piano