Ladies and Gentlemen of the List, I maintain a Yamaha U3 for a church here, which is only one year old, yet has developed "bobbling" hammers on about 25 notes. The immediate cause is that the front edge of the jacks are not all escaping from under the butt buckskin on letoff, althouigh the keydip is "at specs", and the letoff is much more generous than "spec": varying from 5 to 10 mm! My first effort at correcting this problem will be to meticulously regulate this piano to Yamaha factory specs, although I believe that this will only make the "bobbling" worse. I believe that this will occur, as the strange, current "regulation" on this little used instrument ( besides the aforementioned "letoff" distances, the hammers are checking at an inch or more from the strings ) seems to have been effected to overcome some inherent design flaw ( or flaws ) which does not allow the jacks to readily slip out from under the hammer butts. The percieved design flaw to which I refer is a very sharp edge on the plastic jacks' front edge, which seems to catch on the buckskin, causing the butt to bounce upon it repeatedly rather than allowing the jack to fully slip out. This problem may also be exacerbated by the use of an overly "nappy" buckskin, and an unusually sharp angle on the hammer butt buckskin face, at the point where where the jack would normally "trip out". It seems that a tiny bevel, were it filed on the front edge of the jacks, would be efficacious in remedying this "bobbling". I may also try sanding down the butt buckskin and lubricatinmg with some microfine Teflon. My first efforts, however ( after regulating the action ) will be to reduce the hammerstroke, and perhaps increase the keydip by 1 mm. If you please: Have any of you encountered a similar problem on a piano of this model and, if so, how did you approach its remedy? Your advice will be gratefully recieved, Sincerely, Gordon Stelter __________________________________ Do you Yahoo!? Yahoo! Tax Center - File online by April 15th http://taxes.yahoo.com/filing.html
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