the hammer.

5. _Jack_.--The jack itself seldom gets out of order. So long as its
flange does not come unglued in the wippen, or its spring get out of
place or broken, or get tight in its joint, it will need nothing. Its
adjustment and action is controlled by the bottom or capstan, and the
regulating button.

6. _Regulating Button_.--This button determines the point in the
stroke of the hammer where the jack flies off from the nose of the
butt. If the button is too high, the jack does not fly off soon
enough, and the result is, that the hammer either blocks against the
string or bounces from the jack after the stroke has been made,
striking the string a second or third time from one stroke of the key.
The felt punching on the lower side of the button often wears until
this trouble prevails. Lower the button by turning down the screw on
top of the regulator rail; if lowered too far, however, the action is
weakened by causing the jack to fly off too soon, without giving the
hammer a sufficient impulse. A regulating screwdriver is used for
this, but in its absence, a wire hook, similar to a shoe buttoner,
will turn the screw.

The block rail is properly adjusted at the factory and requires no
attention.

7. _Hammer Butt_.--The felts and leather on the heel of the hammer
butt wear out and must be replaced. The felt cushion, that is lowest
and farthest to the left (see illustration), is the one that wears out
first. The jack, in returning to the notch, strikes this cushion, and
in time wears it away so that the jack in returning strikes the wood