When efforts to repair a clock movement have failed, yet the case has value or sentiment attached to it, you can instil a replacement mechanism. Wall and mantle clocks are often equipped with a chime hammer assembly that is included as part of the replacement mechanism. The removal of the old movement and installation of the new can be performed with the proper tools and basic mechanical know-how. The work can be done in one hour or less.
Remove the clock pendulum by lifting it up slightly and off of the suspension rod loop.
Remove the sweep-second hand from the clock if it has one. Pull the sweep hand straight out from its arbor with your fingers. Be sure to grip the hand at its centre hub.
Remove the retaining nut for the clock's minute hand. Support the hand as you turn the nut counterclockwise. If the nut is exceptionally tight, loosen it with combination pliers. Lift the hand off from its arbor after removing the nut.
Remove the hour hand from its shaft by turning it in either direction while pulling it from its centre hub.
Locate the clock mechanism mounting brackets at each of its four corners. Remove the bracket screws that secure the movement to the case by turning counterclockwise while using the appropriate screwdriver.
Remove the mechanism from the clock.
Remove the bracket retaining nuts from each of the corner brackets using the combination pliers. Remove the brackets from the mechanism one at a time, replacing the nut on the mechanism prior to removing the next.
Remove a corner bracket nut from the new mechanism and install a bracket. Be sure to remove only one nut at a time. Replace the nut and tighten clockwise with the combination pliers.
Repeat Step 8 for the remaining brackets.
Install the new mechanism into the clock case by lining up the winding arbors with the holes in the dial. Secure the bracket screws to the case with a screwdriver tightening clockwise.
Check the distance of the chime hammers in relation to the chime rods. When the hammers are at rest, they should be aligned with their respective rods and be approximately 1/8-inch above them. Bend the hammer rods slightly in the middle if an adjustment is required.
Wind the clock mechanism with a winding key until the movement and the chimes are fully wound.
Install the hour hand loosely onto its shaft followed by the minute hand. Turn the minute hand slowly clockwise until the top of the hour strikes. Set the hour hand in place according to the time struck by the clock.
Secure the minute hand with its retaining nut. Tighten the nut clockwise using your hand.
Install the sweep second hand onto its arbor. Press lightly.
Place the clock in its intended position. Attach the pendulum to the suspension rod and set it in motion.
Be sure to write down all the information off of the back plate of the clock movement. Have this information ready when ordering the new movement.