Center pinning. Carefully check the pinning of the hammer flange, rep. lever support, wippen flange and jack center. The hammer, held horizontal should swing down past lowest point seven times. Eight or six are acceptable but barely. If these are white teflon bushings then six is the only acceptable count. There absolutely must be some resistance at the repetition lever support center. Disengage the spring and see if it will drop of it's own weight. If so repin so it requires but a small amount of pressure to move it but not much. A 1 or 2 gram weight on the drop cushion should be sufficient. Wippen centers should be loose enough that the wippen will swing one time while the action is set so the wippen flange is up and horizontal. Too loose or too tight repin. Jack centers should be only tight enough that the jack will slowly move when the long arm is horizontal. Repin as needed. Work on only two or three notes and make them as perfect as you can and have the customer test those notes to see if the problem has disappeared. Regulation. Too much drop can cause such a problem. The drop should be 1 mm below let-off, no more., Some actions may require 11 mm of dip. Backchecking should to set as high as possible, 15 mm or less. Rep. lever height should be set so the jack can move in and out from under the knuckle with it just barely brushing the nap of the leather. Jacks should be set so the back edge of the jack is in line with the back edge of the knuckle insert. Key bushings need to be free, no resistance but no excessive movement, .3 mm front and .2 mm center. Keypins and capstans should be polished with really fine metal polish like Flitz made in Germany. Key bushings and key pins should be lubricated with a dry Teflon spray or powder as should the capstan contact area and the knuckle. Action performance is not one single element but the cumulative effect of careful attention to the minutiae of every aspect of an action. No rest for the righteous. Newton
This PTG archive page provided courtesy of Moy Piano Service, LLC