Yamaha bobbling

[Ron Nossaman]

I've never seen this problem in a Yamaha that's being played like a piano, 
but I suppose it's possible. Typically, this has always been a problem with 
these actions with beginners, kids, and folks with a very tentative touch. 
To me, it looks like a design thing. The ratio of jack length to toe 
(tender) length is high, so any drag of the jack at the butt translates to 
increased resistance at the toe, which is more readily felt at the key. As 
the key is depressed, the pianist picks up resistance from the damper 
spring first. This isn't far into the stroke, isn't out of the ordinary, 
and is ignored. Near the bottom of the stroke, added resistance is 
encountered at letoff, when the jack toe hits the letoff button, and they 
quit pushing. When they don't push through the letoff resistance and finish 
the stroke, it makes the hammer bobble because the jack is still under the 
butt. Assuming the action is in reasonable, though not critically PERFECT 
regulation, the bottom line is that the person playing the piano needs to 
learn how to work it and the "problem" goes away. Since that isn't likely 
to happen immediately, I find the quickest and most easily reversible cheap 
trick is to bend the letoff rail brackets down a tad to make that letoff 
about 1/4" - maybe more. That gets the letoff resistance farther up in the 
stroke where they tend to push through it instead of stopping. There will 
be a point where even the most relentless and determined soft paw won't be 
able to make the hammers bobble. That's where to leave it. Feels funny? No 
power, no control? No sweat. If they were capable of power and control, the 
problem wouldn't have come up in the first place, or at least it wouldn't 
have been a problem unless they are just looking for trouble. Next year, 
when they've learned to work the piano and complain about the lack of power 
and control (or not), these same brackets can be bent back up to get the 
letoff close enough to even it out quickly without having had to crank all 
the buttons down, then up again. Sure, I hate to compromise a functional 
action to accommodate someone's inability to work it, but they aren't going 
to change until (and if) they change, so all that's left is minimizing the 
damage until, and if, they do.

These actions work fine, in my opinion, but just aren't the sloppy and 
infinitely forgiving worn out old spinet or upright action they typically 
replace, and demand some portion of the player's attention to adapt to.

For what it's worth, that's my take.
Ron N