<< I have a customer with a Steinway M Grand which has several notes in octave 3 that make a rattle or knocking noise when played. Do I need to raise the upstop rail, adjust key dip or rebush the guide rail? >> Greetings, I would try the easiest first. Rebush a few of the guide rail holes. The upstop rail has its own set of demands inre placement. Noise isn't usually one of them. When the upstop rail allows the sharp's dampers 1 mm freeplay with damper pedal depressed, you are in the ball park. It is possible that there is some hard surface on the upstop rail that the underlevers are clacking against. Regards, Ed Foote
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