<HTML>PeeTeeGee, You might want to look at backcheck alignment with the catchers.  I= f they aren't making proper contact, , i. e., corners of catchers hitting th= e backchecks, the hammers won't check properly. I've seen this more than onc= e. Dave Stahl In a message dated 6/2/04 7:18:32 PM Pacific Daylight Time, Pianotunaguy= @aol.com writes: <BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-= LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px"> I recently re-flanged my U1 due to bobbling hammers caused by the silk t= hread which holds the hammer butt spring being broken on about half the flan= ges.  Since that day, I have a new problem with the piano: the jack get= s caught under the hammer butt on rapidly repeated notes and blocks the hamm= er to the strings.  This happens on about 10 to 15 hammers in the middl= e of the keyboard. I checked the backchecks and the hammers are checking at 5/8".  I c= hecked the lost motion and there was enough to allow the hammers to move bac= k with the hammer rail when pulled away from the strings.  There is eno= ugh dip to allow the jack to letoff.  </BLOCKQUOTE> </HTML>