[pianotech] Weekend puzzler

[John Delacour]

At 23:09 -0700 15/07/2011, Delwin D Fandrich wrote:

>...As the key is depressed slowly-pianissimo-for the first 
>millimeter or so the key and hammer move smoothly. Then something 
>starts binding, it feels like something in the action is dragging, 
>holding the key and action back. After forcing the key down another 
>three or four millimeters action becomes free and everything 
>operates normally. On a medium to hard blow there is good power and 
>the problem is hardly noticeable but at pianissimo the action will 
>hardly play.
>
>What is the problem and what caused it?

Sounds like the check catching the hammer on the way up, which would 
be caused by the lowering of the hammer rest position (too much 
blow), increase in lost motion in the jack window, slightly high 
setting of the check position or a combination of all these three 
things.  However, I would expect the problem to be a bit more than 
"hardly noticeable" under a hard blow.

JD