Switch off the electrical power at the main breaker or fuse panel to the doorbell circuit.
Access the doorbell chime box from a ladder or step stool and remove the doorbell chime cover from the chime assembly. The doorbell chime box is usually located on the wall near the front door.
Disconnect the small wires connected to the doorbell chime leads in the center of the chime assembly. Homes with one doorbell button location will have two connection wires. If your home has two button locations, there will be a third wire, connected to a lead labeled “C” or “common”; this wire should be marked with masking tape.
Detach the old doorbell chime box using a screwdriver by loosening and removing the screws holding the base to the wall.
Mark the new mounting holes, if applicable, by holding the new doorbell chime box in position on the wall, then pencil-mark the wall at the new screw hole locations. If the old screw anchors align with the available holes in the new chime box, the old screws and anchors can be reused.
Drill a 3/16-inch hole at each screw location with the drill, if applicable, and insert plastic wall anchors into each hole.
Insert the doorbell chime wires through the back of the new doorbell chime box base, then hold the base against the wall. Use the screwdriver to insert the No. 12 screws through the base into the wall anchors and tighten.
Attach the circuit connection to the new doorbell chime box by wrapping the end of the doorbell wires clockwise around each terminal screw base and tightening the screws with a screwdriver. Connect the common wire marked in Step 3, if applicable, to the C terminal. The remaining two wire connections are interchangeable and can be attached to either terminal.
Hook the top of the chime cover over the chime, then lower to snap the cover onto the chime base.
Restore the electrical power to the doorbell circuit at the main breaker or fuse panel.