In order for the clock to go satisfactorily, it must be set in beat. A clock
is 'in beat' when the intervals between ticks are exactly equal. An 'out of
beat' can be heard ticking unevenly, with alternately long and short intervals
between ticks.
Carefully fit the pendulum, wind the mainsprings and
gently set the clock going. After a few moments check the sound of the ticking.
If it is not even, proceed as follows:
Stop the clock by holding the
pendulum in the central position. Carefully move the pendulum from side to side
just enough to allow the ticks to be heard, and check which direction requires
the least movement from the vertical position. It is in this direction that the
crutch (the part that delivers the power to maintain the swing of the pendulum)
needs to be bent.
The aim is to alter the position of the crutch in
relation to the escapement and it is important to establish what provisions the
manufacturer has made to enable this to be done.
Many movements have
friction joints which allow the crutch to be adjusted without bending. To adjust
these, move the crutch in the desired direction to the limit of its free travel
and then apply slight pressure. If the movement is fitted with a friction joint
the crutch will move further with an even resistance. If the crutch starts to
flex, let go at once. If movement of the crutch is restricted by, for instance,
pins protruding from the back-plate, the escapement will have to be held with
one hand while the crutch is moved.
Where no friction joint is fitted,
the crutch needs to be bent. Never put any firm pressure on a crutch against the
escapement as this may do serious damage. Always bend the crutch against the
resistance of the other hand or between fingers of the same hand. Whichever
method is used, several attempts may be necessary as there is no way of
measuring the alterations you are making. Only make very small adjustments each
time.

Adjusting the beat where no automatic provision is
available.
Wall clocks may be given their final adjustment by moving
the bottom of the case very slightly to one side. Some fine movements have
screw-threaded beat adjusters, allowing for very precise
adjustments.
French clocks:
If the movement is fitting with a
friction joint, the crutch will move further with an even resistance. If the
crutch starts to flex, let go at once and adjust in the conventional
manner.
Final adjustment is sometimes made by slackening the two screws
on the back door and rotating the whole movement imperceptibly. Re- tighten the
screws to prevent the clock from rotating when being wound.
Repairing Your Own Clocks by Mervyn Passmore