Hi Todd:
I remember working on one many years ago. The tray that engages the tabs on the damper levers must be carefully adjusted. It's the equivalent to the sostenuto blade in a grand. But the hard part is adjusting the tabs, or in the case of Mason and Hamlin, a sharp sticker. I recall trying to bend the stickers while the action was in the piano, which was almost impossible. The trouble is, the damper levers depend upon the dampers resting on the strings, so you can't remove the action to regulate the stickers. If you could immobilize the dampers/levers so that they wouldn't move when you removed the action, it might make it doable on the bench. All you'd need to do is to set a few, and then adjust the rest in a straight line. I can't recall if the sos tray is attached to the action, and thus removed with it. Also, I think there is some kind of covering of the tray that cushions and reduces clicking noise from the stickers. Often that covering is deteriorated or missing. As well, I think I remember a spring arrangement to pull the tray away when you release the pedal. I recall the whole thing was not very precise and rather crude.
I wish I could tell you exactly how to proceed, but I can only encourage your efforts. I'm sure somebody has a better answer.
Good luck.
Paul McCloud
San Diego
Original Message:
Sent: 1/1/2021 7:32:00 PM
From: Todd Loomis
Subject: Mason & Hamlin Model 50 Sostenuto
I have recently encountered my first need to adjust an upright sostenuto, this one in a Mason & Hamlin model 50 upright. Before just plunging in and figuring it out on the fly I thought it would be prudent to get pointers from someone who has worked on these before. Do any of you have any advice, or perhaps a Journal article you could point me to? Thanks?
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Todd Loomis
Stanwood WA
360-631-9045
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