action reg puzzler on M & H BB

[Jon Ralinovsky]

Hi Mark,
Is the end of the rep spring that goes into the jack a little long or 
otherwise binding in the jack mortise?

Respectfully,
Jon


>List -
>
>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.
>
>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.
>
>If anyone can shed some light on this puzzler I would be most grateful!!
>
>Mark Potter


-- 
Jon Ralinovsky
Piano Technician
Department of Music
Miami University
513/529-6548