Wall clocks, like free-standing pendulum clocks and mantel clocks, work by winding gears that turn weights and other mechanical instruments. These are known as "movements." Like any other mechanical device, a wall clock needs regular maintenance for a longer life and more accurate time keeping. When a wall clock ceases to work, a likely source of the problem is an old movement that has worn out. To replace a wall clock's movement, you'll need a few hand tools.
Unhook the pendulum, if the wall clock has one.
Unfasten the retaining nut holding the minute hand in place by twisting it counterclockwise. Use pliers if necessary. Once the minute hand is unfastened from the shaft, pull off the hour hand.
Unfasten the movement's mounting brackets with a screwdriver. The mounting bracket will be secured to the clock's base in at least two places and as many as four places.
Pull the wall clock out of its casing.
Unfasten the movement's retention screws or nuts with a screwdriver or pliers and carefully pull out the old movement. Take note of the old movement's positioning with respect to the shaft and winding arbors as the new movement will have to be positioned precisely the same way.
Position the new movement onto the shaft and line it up with the winding arbors in the same manner as the old movement.
Replace the retention screws or nuts. Put the wall clock back in its casing and replace the mounting bracket. Put the hour and minute hands back on, as well as the pendulum. Replace the retaining nut to hold the hands in place on the shaft.