All clocks must have maximum power transfer to the pendulum or they will not run dependably. This means they must be in beat. What does this mean? Some call this “setting the balance”. Try to imagine the pendulum and verge as a swing and the person pushing as the escape wheel. When the clock is in beat the escape wheel gives the pendulum a push at just the right time in the same way as a person gives the swing a push just as it arrives back and at the instant it starts back on its return trip. When a clock is not in beat the situation is similar to the person pushing the swing taking five or six steps forward before the person on the swing starts on their way back. What happens? There is a collision and the arc of the swing is disturbed. If a clock is out of beat the verge collides with the escape wheel teeth, and the clock eventually stops before it is run down.
The verge clutch will usually allow the beat to be set by adjusting the position of the impulse arm until it is at the true center at rest with the mechanism and case set level and plumb. Be very careful when setting the beat; sometimes the verge clutch is set so tight that the escape wheel teeth can be bent without realizing it. If the clock is “in beat” then as you watch the pendulum swing you will hear a “tick” or “tock” precisely at the point when the pendulum passes the center ( true center as mentioned above) of its arc. This must be its characteristic arc , not the one you give it when you swing the pendulum. How do you know its “true arc” ? Do this with the clock perfectly level while you can see the escape wheel and verge: starting with the pendulum at rest move it slowly until you hear a tick or a tock which is the sound of the escape wheel releasing.(You must know which way to move the pendulum of course because the escape wheel will only release once on each side of the arc. If you are doing this for the first time it would be a good idea to be able to watch the escape wheel and verge interaction so as to know which way to move the pendulum to allow the verge to release the escape wheel. To get an idea how this works, take the pendulum off and GENTLY move the suspension arm back and forth to observe and learn the action of the escape wheel / verge combination, then put the pendulum back on and continue.) As soon you hear the tick or the tock release the pendulum. DO NOT PUSH IT. If the clock is in beat you will hear the other side tick when the pendulum gets to the other side of its arc.
If the beat is set, but the clock gets in beat and they out of beat; check for bent escape wheel teeth if the “in beat and out of beat” sound has a regular repeating pattern. If there is not a regular pattern then the problem is probably a loose verge. The clutch can be ok but the verge can be loose on the shaft. when setting the beat on a clock, if possible do it by sight and sound.
Setting the beat on a balance wheel is just as important as the beat on the pendulum units. The hairspring collar can usually be moved if need be, it is a delicate operation. Practice on spare parts