Check to see if the backchecks are hitting the sostonuto rail. Other possibility, the keys or key buttons hitting the fall board. If the nuts holding the key stop rail in place are loose it also can make a clicking noise. Other 'knocking' noises can come from hard knuckles, eitgher felt or leather, hard rocker felt and hard backrail felt. Get the wire brushes out. If the keys are chucking becuase the bottom hole is enlarged then you can get such noises, as has been mentioned. All this is assuming that there are no extranious matter in the action, like pencils, etc. It is also possible, less likely though, that the damper levers have loose teflon bushings that are causing some noise. Check that out early on. Check that the knuckles are firmly glued in place and that the knuckle covering is also. Hope this helps. Newton nhunt@jagat.com
This PTG archive page provided courtesy of Moy Piano Service, LLC