Hi Annie I'll tack Alans reply on below. Double check the strength of both damper springs and jack return strings (by feel) They dont need to be any stronger then is enough to do their respective jobs. Also double check damper timing to be at half blow. If timing is to err, then let it be just barely late rather then early on these pianos. (MHO) but dont get carried away :) The jack return springs may seem puny... but a bit of experiementing with different spring strengths can be enlightening. Cheers RicB Howdy Ric, et al., The jack tops did appear to be unreasonably close to the butts, which I wondered about. And, yes, the double-strikes are a soft-blow phenomenon. But I could feel the hammers wobbling when I played before starting tuning, and I'm not about to leave customers with that, even if they'd never recognize (or probably even notice) the wobble. I thought the jack return springs looked pretty puny, but maybe looks are deceiving in this case. When did Alan deal with these issues in older instruments? I haven't seen any such reply to my query, so I'm wondering whether I missed something (as usual <g>). Thanks! Annie ------------------ Piano owners are usually not happy when their pianos have the "automatic staccato repetition feature," that is, bobbling (technical term: double-striking) hammers. Here are common causes and cures: *Verticals:* Possible Causes: Inadequate key dip for the hammer stroke caused by hammer wear and/or rest felt wear/compaction; backcheck felt wear; catcher buckskin worn, damaged, or missing; checking distance too far; excess lost motion between jack and hammer butt. Other actual or contributing causes may be weak hammer springs (especially the Schwander-type butt spring), poorly shaped or worn butts (not yours, the piano’s), too little lost motion so that the hammer, at rest, is physically touching the jack (use the rest rail follow test for a quick check: There must be some lost motion); butt flange center pinning too loose. Thickness of the butt felts helps determine the jack angle as it hits the butt, which can contribute to bobbling. A rare cause is misalignment of the action or capstans in the piano, usually a manufacturing goof. Cures: Make necessary repairs. Make sure keys are level and that the backrail felt is in reasonably good shape. Regulate blow, lost motion, letoff, and checking. Check dip—make sure there is adequate aftertouch for the action to completely cycle and the hammer to check before the key bottoms out— but there must be no excessive lost motion or "slop". If the problem persists, it may help to gently hyperflex the hammer return spring to strengthen it—and make sure it moves freely in its felted slot. Sometimes removing some of the slack from the bridle strap can help. Make sure nothing is interfering with action movement, e.g., bent bridle wires. Less common, but noticed in newer Yamaha uprights, damper springs (or jack springs) may be too strong or damper spoons regulated in such a way that resistance becomes very high at the same time that the jack spring is being compressed for letoff. To check this, depress the right pedal and see if the bobbling stops. You may need to ease the spring or change spoon regulation. *Grands* Regulation is always the suspect, here. If the bobbling happens on a hard blow, it is likely that the hammers are not checking properly. The backchecks may need new leather and/or regulating. Worn or missing key bushings can cause the key to flop around so much that checking is affected. Evaluate the repetition lever spring and the amount of hammer drop: If the spring is too strong and/or drop is too high, bobbling may occur on soft blows. Alan Barnard Salem, Missouri
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