I don't believe I've heard key dip mentioned in any of these conversations. My first reaction to bobbling hammers is insufficient dip. For a player mechanism, the dip would be a function of how far up the player pushes on the back of the key. First I would look for lost motion between the back of the key and whatever pushes up on it from the player mechanism. If there were no lost motion then I would ask the manufacturer how much stroke the mechanism makes and if there is any adjustment of this. If not then I would surmise that the only way to prevent bobbling is to settle for a higher hammer line. David C. Stanwood
This PTG archive page provided courtesy of Moy Piano Service, LLC