If you still have mechanical clocks around the house, here's how to fix them.
If the clock has a pendulum, remove it before disassembling the clock.
Inspect the mechanism for damage, then apply lightweight lubricant as needed.
A clock is an instrument for measuring and displaying time. Mechanical clocks are driven by spur gears that are powered by either a falling weight or an unwinding spring that turns the hands at a precise rate. The main shaft then turns the hour, minute, and sometimes second hands around the clock face to indicate current time.
To clean a mechanical clock:
Carefully remove the clock mechanism from the case.
Pour a cup or two of turpentine or paint thinner in an empty coffee can or similar metal container.
Place a small-mesh screen or cheese cloth over the top of the coffee can and, if necessary, secure it to the can with a rubber band around the can's perimeter.
Set the clock mechanism securely on top of the can so the chemical vapors reach the internal parts.
Allow the vapors to work on the clock mechanism for at least 12 hours before removing. Carefully use a small brush to remove any debris.
Lubricate the clock (see below).
To lubricate a mechanical clock:
Carefully remove the clock's back cover to access the interior of the clock. Some models require that the clock mechanism be removed from the case.
Visually locate the working gears in the clock. If possible, wind the clock and watch it run for a few minutes to determine which are moving parts.
Use lightweight oil to lubricate gear shafts sparingly. Wipe away excess oil.
Replace the clock back or the mechanism in the case.