The collection of gears inside a mechanical clock moves a clock's hands. Powered by weights or springs, the "movement" or clock mechanism keeps accurate time when properly lubricated to permit free movement. When lubricants thicken, movements gather dust and grime, slow down or seize. To clean a clock movement, open up the clock and remove all debris.
Open up the back of the clock, using a screwdriver if necessary. The movement should now be visible. If the clock has a pendulum, remove it.
Inspect the clock movement for debris, such as lint, or semi-solidified oil build-up. Use a soft cloth to remove these deposits. Spray the movement with compressed air to eliminate finer dust and lint. Use the nozzle on the can to direct the flow of air into hard-to-reach areas.
Place some clock cleaning solution on the soft cloth. Do not make the cloth too wet. The movement should not be flooded with cleaning solution. Make a clock cleaning solution by mixing eight parts ammonia to one part commercial liquid cleanser, and one part oil soap. Use the soft cloth to rub off grease and grime that's stuck to easy-to-reach parts of the movement. Do not force the cloth into tight areas, as small parts might break.
Dab some clock cleaning solution onto a cotton swab. Insert the cotton swab into difficult-to-reach parts inside the clock movement. Rub gently to remove grease and grime.
Check the movement's gears to see if they move freely, by gently manipulating the various parts with the hands. Place a small amount of clock oil on a soft cloth. Clock oil is a special preparation available from retailers. Do not use motor oil, or WD-40, as these may clog the movement. Lubricate only those parts that already have oil. All parts of the movement do not have to be lubricated, but those that do, vary from movement to movement. Use the soft cloth to lubricate parts that are easily reached. Put some clock oil on a cotton swab to lubricate smaller, or hidden parts inside the movement.
Reattach the back of the clock, using a screwdriver if necessary. If the clock has a pendulum, put it back on.
Regular cleaning is necessary to keep clock movements in good working condition. Worn parts inside old movements will still have to be replaced from time to time.
Do not disassemble the clock movement if you are not sure of how to put it back together. Clock movements are extremely complex. If the clock still does not work properly after a simple clean, take it to a professional clockmaker or clock repair expert.