Things You'll Need
Ruler or tape measure
If the cuckoo begins to run too slow after the first adjustment, raise the leaf on the pendulum rod to halfway from your first pencil mark.
Cuckoo clocks are both a work of art and an operating timepiece. With a variety of features available on many different models, cuckoo clocks have become a favorite in households throughout the world. At times, a cuckoo clock can run too fast, making an adjustment necessary. This adjustment of the cuckoo clock will regulate its timekeeping to a slower pace that will bring it within an accurate timekeeping range. The job requires patience, observance and a gentle touch.
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Remove the pendulum from the cuckoo clock. This is the wooden rod with an attached leaf pattern suspended below the clock. To do this, stop any motion of the pendulum and shine your flashlight to see through the slot at the bottom of the cuckoo clock. Follow the rod up to find a metal hook. The hook passes through a wire loop: Lift the pendulum rod slowly and gently to remove it from the loop. Take the pendulum rod out of the clock.
Mark a line across the back of the pendulum rod with a pencil where the leaf brackets are fastened. This mark will be for measuring reference.
Move the leaf down the pendulum rod 1/4 inch. The leaf is designed to be moved by hand. It is held in place with metal brackets on both sides, which allow it to be moved up or down according to timekeeping needs. Mark this spot with a line across the back of the rod with a pencil.
Place the pendulum rod hook back through the wire loop with care.
Set the time on the cuckoo clock with another clock in the home that you known keeps accurate time.
Raise the weights of the cuckoo clock all the way up.
Move the pendulum gently in either direction about 1 inch and release it. This will be sufficient for the cuckoo to begin operating again.
Allow the cuckoo clock to run for a day, then check the time. If the cuckoo is still running fast but not as much, move the pendulum leaf down a little more.
Mark each spot for reference and repeat this process until the cuckoo clock is keeping accurate time.