The stopper in your kitchen sink acts as a valve, controlling the flow of water into the drain. Open, the stopper allows clear passage of water to the drain; closed, it forms a seal around the entrance to the drain. A faulty or damaged stopper fails to do either. A homeowner with modest repair skills can replace a flawed stopper valve in just a few minutes.
Open the cabinet door beneath your kitchen sink to reveal the sink's drain pipe. Clear enough room beneath the sink to allow ample work room.
Look behind the drain pipe for a pivot rod. The rod extends horizontally from the rear of the pipe. Use a flashlight, if necessary.
Follow the pivot rod to where it attaches to the drain pipe. A retaining nut at the end secures the pivot rod to the pipe.
Turn the retaining nut counterclockwise until loose. Slide the the pivot rod from the side of the drain pipe.
Return topside to your kitchen sink, and pull the stopper free of the sink drain.
Fit the new stopper into the sink drain. Arrange the stopper so that the eye on the bottom faces the rear of the sink.
Return beneath the sink, and fit the pivot rod back into the side of the drain pipe.
Turn the retaining nut clockwise until it is snug against the pipe.