<HTML style="FONT-SIZE: x-small; FONT-FAMILY: MS Sans Serif"><HEAD> <META http-equiv=Content-Type content="text/html; charset=windows-1251"> <META content="MSHTML 6.00.2900.2963" name=GENERATOR></HEAD> <BODY> <P> <DIV>Mark Potter asked: " <DIV><FONT size=+0>List -</FONT></DIV> <DIV><FONT size=+0></FONT></DIV> <DIV><FONT size=+0>I am having a puzzling problem with a M & H BB grand action that I have never encountered. Complete regulation (w/new shanks& hammers), everything works great with the exception of 3 notes - F6, A#6, G7 - in the high treble. I cannot get this to happen on the bench, and even in the piano when the notes are played softly, even in a trill, they perform perfectly. However, under continuous mf - ff blows, as in tuning, after anywhere from 1 to 10 strikes (letting the key all the way up), the hammer will get caught on it's way back up by the back check, thereby not allowing it to strike.</FONT></DIV> <DIV><FONT size=+0></FONT></DIV> <DIV><FONT size=+0>I have tried numerous adjustments to the angle of the back check as well as to the height of check for these 3 notes, to no avail. Everything seems to be identical to the surrounding notes, including jack reg - both in the window and to the knuckle core -, rep spring strength, key dip, stroke, the arc of the tails, let-off, drop, etc., etc... you name it. Keys are rebushed and moving freely.</FONT></DIV> <DIV><FONT size=+0></FONT></DIV> <DIV><FONT size=+0>If anyone can shed some light on this puzzler I would be most grateful!!"</FONT></DIV> <DIV><FONT size=3></FONT> </DIV> <DIV><FONT size=+0></FONT></DIV> <DIV><FONT size=+0>Mark,</FONT></DIV></DIV> <DIV>My first guess would be that the Jacks are hanging up.</DIV> <DIV> </DIV> <DIV>Joseph Garrett, R.P.T.</DIV> <DIV>Captain, Tool Police</DIV> <DIV>Squares R I</DIV> <DIV> </DIV> <P></P></BODY></HTML>