If it's not what Jim said, I would look into the possibility that the sostenuto rod bracket screws in the bass and possibly at the bass / tenor break are loose, allowing the bar to have migrated towards the sostenuto tabs in that part of the scale when the hammers were filed.
Alan
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Alan Eder, RPT
Herb Alpert School of Music
California Institute of the Arts
Valencia, CA
661.904.6483
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Original Message:
Sent: 05-06-2021 07:28
From: Jim Ialeggio
Subject: S&S dmapers hanging up after service
It's the sostenuto hanging up. I've had this happen. I'd go with the metal brackets in the cheek blocks, or the cheek blocks themselves. If cheek block dowels are worn, or the brackets slightly worn, the action will not go back in exactly where you want it. I'd increase the clearance between sostenuto and tab pickups on the damper top flange, by adjusting the silly S&S sostenuto mechanism.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 05-06-2021 05:53
From: David Weiss
Subject: S&S dmapers hanging up after service
My son, who works with me, serviced a S&S B yesterday. He said it was in good condition. He tuned it, did a light hammer filing, and some voicing. When finished, he put the fallboard, cheek blocks, and keyslip back in and as he started playing, some dampers were hanging up. Mostly in the bass and low tenor. If he removed the cheek blocks and pulled the action out just a 1/16 of an inch, the dampers would drop down. But every time he put the cheek blocks back in and screwed them down the problem returned.
We did some trouble shooting over the phone but could not solve the problem. He said there did not seem to be interference from the sostenuto rod or sostenuto tabs. He did not leave any tools inside the action cavity. The metal brackets mortised into the cheek blocks are screwed in tight. The guides on the ends of the key frame are secure and not bent.
The piano played fine before he did any work. I am going out there later today. I can't think of any way the position of the action could change or what could be causing the interference.
Thanks,
David Weiss