Fixing a clock that runs too fast can be as easy as turning a screw. Clocks with either an interior or exterior pendulum have adjustment screws either on the pendulum or through a hole in the top of the clock. It may take up to two weeks to properly set a clock that is running fast.
Hold the pendulum in your non-dominant hand. Look for a small screw at the bottom tip of the pendulum. This screw regulates the speed of the clock.
Use the fingers of your dominant hand to gently turn the regulation screw. Turning the screw to the left will lower the pendulum slightly and slow the clock down. Each turn of the screw slows the clock by two minutes per 24-hour period.
Check your adjusted clock against a reliable timepiece several times over the course of a day and continue making adjustments until your clock is properly set.
Locate a small hole on the top of your clock. There may be the words 'fast' and 'slow' marked around the hole to direct you in setting the clock's speed.
Insert the narrower end of a double-ended key into the hole.
Turn the key gently to the left, or the direction indicated on the top of the clock, to slow the clock down. One full revolution slows the clock by two minutes per 24-hour period. Check the clock against a reliable timepiece several times during the day and adjust as needed.
Set the time on your non-mechanical electric or battery-powered clock to match an accurate timepiece.
Keep an eye on the time for 24 hours to ensure that your clock is running fast and has not just been set improperly.
Plug your clock into a plug in a different room and test the time again for 24 hours. It is possible that your outlet is not providing steady electricity to the clock. If you have a battery-powered clock, replace the batteries.
If your clock still appears to be running fast after taking these steps, bring the clock to a repair shop for maintenance. It is possible the motor is faulty or broken.