Some basic steps to repair a grandfather clock are to realign the weights, unlock the hands, shift the pendulum bob down or up in the shaft, reset the moon dial and level the clock. To repair an unmoving pendulum, wind the weights, and unlock the hands.
To realign the grandfather clock's weights, place them on the appropriate side as per the markings indicated. This helps the clock to keep time accurately. To wind the weights, pull them up. This allows the weights to power the clock's pendulum.
To unlock the clock's hands, pull the weights of the clocks up, open the glass on the timepiece's face and separate the hands. To do this, gently press the hour hand towards the clock, or pull the minute hand slightly away from it. If needed, bend the clock's hands away from the glass. This allows the pendulum to swing normally again. If the pendulum runs too fast or too slow, unscrew its bob, and move it down or up the pendulum shaft.
To reset the moon dial, open the clock's glass, apply gentle pressure on the dial and rotate it to show the current phase of the moon. To level the clock, place it on an even surface, or adjust the leveling. Once placed, check to see if the clock is levelled by using a spirit level.