<HTML><HTML>I recently re-flanged my U1 due to bobb= ling hammers caused by the silk thread which holds the hammer butt spring be= ing broken on about half the flanges.  Since that day, I have a new pr= oblem with the piano: the jack gets caught under the hammer butt on rapidly = repeated notes and blocks the hammer to the strings.  This happens on = about 10 to 15 hammers in the middle of the keyboard. I checked the backchecks and the hammers are checking at 5/8".  I chec= ked the lost motion and there was enough to allow the hammers to move back w= ith the hammer rail when pulled away from the strings.  There is enoug= h dip to allow the jack to letoff.  The piano does get a lot of use; I teach 15 students/week on that piano.&nbs= p; The piano is about 30 years old and these are the original butts.  = So I could imagine that the butts have finally worn to the point that there= is a dent or something catching the jack under the butt.  I thought t= he next thing I would try is to apply Teflon powder to the butts.  (An= d remove one and take a good look at one...) But it seems unlikely that this problem didn't exist and then all of a sudde= n 15 of them all develop this problem at the same time.  Am I missing = something?  Can anyone offer me some advice? Thanks PianoTunaGuy </HTML>