This same tooner diagnosed a cracked soundboard in another grand as the source of a buzz in the piano. He took the Yamaha C-3 , not the one in the photo, to his workshop and performed the identical job buttons and screws , charged her a few thousands, returned the piano and a little later the buzz returned. My fellow RPT buddy came to the client's rescue and repaired the buzzing in short order.
It was the pedal lyre support rods.
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