While cuckoo clocks are capable of keeping good time, many owners enjoy their clocks more for the sounds they make. The very first cuckoo clock was crafted by Anton Ketterer in 1738 and used two air bellows and two pipes or flutes, to produce the two distinctive cuckoo tones. In time, though, the bellows material can develop leaks which cause the tone of the flute to diminish and finally stop altogether.
Pull the cuckoo clock weight chains downward and raise the weights to their uppermost position.
Remove the weights from the cuckoo clock chain hooks and set aside
Remove the pendulum from the clock by gently raising it up approximately 1/2 inch and away from the center of the slot at the bottom of the clock case. Use a flashlight if needed to observe the pendulum hook to ensure it has been disconnected before attempting to remove it.
Remove the cuckoo clock from the wall. Keep the clock in an upright position while moving it to the work area and while it is being worked on.
Remove the back access panel from the clock by raising it up and outwards.
Use the flat-jaw pliers to pry open the lift wire from the looped pin that is attached to the upper part of the bellows. There is one wire connected to each of the two bellows assemblies that are mounted on either side of the case interior. If both bellows are to be replaced, remove only one at a time.
Remove the screw on the outside of the case beneath the sound hole that secures the flute and bellows using a screwdriver.
Remove the flute and bellows from the cuckoo clock case.
Remove the top of the bellows to be replaced by cutting it off from the lower part using the utility knife.
Hold the flute tube firmly in one hand and grasp the lower part of the bellows with the other and with a quick snapping action, break the lower part of the bellows off the flute tube. The old glue will separate with little to no resistance.
Use the utility knife to remove old glue residue and medium-grit sandpaper to smooth any rough areas on the top of the flute.
Remove the lift pin loop from the old bellows top using the flat-jaw pliers. Pull the pin straight out from the bellows wood.
Install the lift pin using the flat-jaw pliers into the top part of the new bellows assembly in exactly same area as it was located on the old bellows top. Make sure to hold the upper and lower parts together firmly when installing the pin into the wood to avoid damaging the new bellows material.
Place a thin ring of wood glue around the flute tube air hole at the top of the flute.
Fasten the new bellows onto the top of the flute tube by lining up the bellows air hole at the bottom of the bellows with the flute tube air hole at the top of the tube. For positioning reference, the flute tube sound hole on the side of the tube will face to the right and the bellows pin loop will be facing to the left. Follow the wood glue manufacturer recommendations for setting time before installing assembly into the cuckoo case.
Install the bellows and flute assembly into the cuckoo clock case and secure tightly with the retaining screw from the outside of the case using the screwdriver.
Attach the lift wire to the bellows pin and close the loop in the wire using the flat-jaw pliers.
Replace back access panel.
Hang the cuckoo clock back onto the wall.
Install pendulum onto the pendulum rod. Use the flashlight if needed to line up the pendulum hook.
Attach cuckoo weights onto the chain hooks.