t the jack will be found to set so low that there will be lost
motion in the key. In this case, loosen one of the screws in the
bottom and turn the other down so as to move the jack upward until
nearly all lost motion is taken up. A little play is generally
necessary, but very little. In case the action has a capstan, simply
turn it upward.

3. _Back Check_.--Blocking is most usually caused by the back check
being too near the back catch, so that when the key is struck, the
back check holds the hammer against the string. This should be seen
after raising the bottom or capstan as above referred to. It will be
observed that when this is done on account of the wear of the felts,
the back check will stand much nearer the back catch than it did
before, and will need bending back so as to give the hammer plenty of
"rebound." A steel instrument with properly shaped notches at the
point, called a regulator, is used for bending wires in regulating the
action. See that the wires stand as nearly in line as is possible. In
old actions that are considerably worn, however, you will be obliged
to alter some more than others.

4. _Bridle and Bridle Wire_.--In putting in a new bridle, it should be
doubled over at the end and secured to the hammer butt by a small
tack. Be sure you get it exactly the same length as the others;
otherwise it will be necessary to bend the bridle wire out of line.
Some tuners glue the bridle around the back catch stem, but the above
method is preferable.

The purpose of the bridle is to jerk the hammer back quickly and the
wire must be set, neither so far back as to check the stroke of the
hammer, nor so far forward that the bridle is too slack to draw upon
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 butto