<html> Tom, Before compromising the letoff that much, I would try to increase the key dip by shimming up the balance rail - about the thickness of a business card.  Jerry Gravina, RPT Babylon, NY At 12:06 AM 03/07/2003 -0500, you wrote: <blockquote type=cite class=cite cite>List             I recently serviced a U1 vertical for a first time client. Excellent piano very little wear and -tuned up quite well.             I did however find lettoff to be over !/4 and inconsistent.             I adjusted to 1/8 and took up lost motion. Tightened action screws. The key dip and after touch were sufficient, and the jacks are free to travel away from the butts---no interference from that adjustable rail (sorry, I forget Y s nomenclature on that component)             My client has a light touch and the action still stutters I returned, shortened blow distance readjusted lost motion, and adjusted spoons to re-correct damper timing.             My client called again with the same problem and called other technicians for advice also              I know bobbling hammers can be a problem on Yamaha verticals and I ve worked on hundreds of these, but I can t shorten blow any more and as I mentioned, keydip-aftertouch are correct. I m hesitant to increase lettoff back to its original excessive amount, so esteemed colleagues ---Any suggestions? I m going back next week.             P.S.  Backchecks are also adjusted---I.E. catchers are not bouncing out or off of the backchecks             Tom Driscoll RPT</blockquote></html>