succession in which motion is transmitted.

1. _Key_.--Keys stick; that is, after being struck, they fail to come
up quickly, if at all. First ascertain if the trouble is really in the
key, or in the upper part of the action. To do this, lift the
extension or wippen until the upper part of the action is entirely
free from the key, so that you may test the key independently. Some
keys are leaded so that they will fall in front of the balance rail,
others so that they will fall back of it; in either case, lift the low
end and let go, to see if it will fall by its own weight. If it seems
quite free, you may know the trouble is not in the key; you will also
find that when you release the extension or wippen, it will not fall
readily, showing that the trouble lies in the upper part.

If the trouble is found in the key, examine the guide pin. See if it
is placed in a direct line with the key. If so, and it still binds,
enlarge the hole by pressing the wood back slightly with some
wedge-shaped instrument, if you have not a pair of the key pliers
which are used for this purpose. See that the cloth, with which the
hole is bushed, is not loose and wrinkled. Do not oil or grease the
guide pin unless such treatment has been previously resorted to, as
the polished pin will work more freely in the dry cloth. Do not pinch
hard on the pin with rough pliers and spoil the polished surface.

Sometimes you will find one key warped so that it rubs on the next, in
which case, plane off a slight shaving to free it. Sometimes changing
the position of the guide pin will straighten or level the key and
make it work all right.

The balance pin is subject to some of the same difficulties as the