Yamaha U1 regulation problem

[Tom Driscoll]

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            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


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