A pendulum is a device that is most often found in Grandfather clocks, both antique and contemporary, but is also used in mantle, wall and Grandmother clocks. The pendulum is located at the front of a clock; it is responsible for regulating the timing of the clock, from slow to fast. The pendulum is located in front of the weights, which work with the inner mechanisms of a clock to help it keep accurate time. If the pendulum is faulty, it has to be replaced. Replacment pendulums can be found through clock manufacturers and clock collector's associations.
Examine the pendulum on the front of the clock to make sure it is hanging correctly. If something is wrong with the pendulum, it can affect other parts of the clock's mechanisms. Unhook an old or faulty pendulum from the pendulum hook. Take a replacement pendulum that is the same size as the original and hang it in place, making sure the shiny side of the pendulum bob is facing front. Faulty parts elsewhere in the clock can affect how the pendulum works, too.
Check the speed of the new pendulum. Sometimes a pendulum swings too slowly, which interferes with the rhythm of the clock's mechanisms. Adjust the pendulum nut to make the pendulum swing faster, if necessary. Don't let the pendulum swing too fast or it will be prone to wear.
Unhook the pendulum and set it aside. Examine the weights on the clock. See that the weights are hanging in the correct order. Look on the bottom of the weights, where they are marked "Front," "Left" and "Center." Fix the weights if they are twisted, and make sure they are not hitting the back of the pendulum. Replace the new pendulum on the hook.
Contact a clock repair specialist if you continue to have problems with the pendulum.