The seat disk predates the Korky flapper, so your toilet must be really old if it has a flush valve that uses one. It’s a flat rubber disk that fits over the valve opening, held in place by water ...
Step 1: Shut-off the water. Find the silver shut-off valve on the wall just below the tank. Close the valve by turning it clockwise to prevent the tank from refilling while you’re working.
Nothing gets under a parent’s skin like lights on in empty rooms, open doors and windows and running or gurgling toilets. Of course, we’ll probably never have children that stop doing the first two, ...