A pop-up stopper is definitely a convenience when it's working properly, but all too often it isn't. The culprit is often an accumulation of hair in the drain, but sometimes the lever mechanism sticks or just comes apart. If you want to fix it yourself, the only requirement is a willingness to crawl under the sink and work in close quarters. Bring a headlamp so you don't also have to work in darkness.
Understanding the Mechanism
Before you roll up your sleeves, taking a moment to understand how a pop-up stopper works will minimize the amount of time you have to spend on the repair. The stopper itself is part of a long plate that fits down into the drain tailpiece. The plate has a hole at the end that lines up with a lever inserted through the tailpiece. The lever connects to the lift rod by a metal plate called the clevis, which has a series of evenly spaced holes. You connect the stopper by inserting the lever through one of the holes in the clevis -- you can adjust the action of the stopper by choosing a different hole.
The Stopper Won't Lift
When you get under the sink, the first thing to do is make sure the clevis is firmly connected to the pull rod. If not, tighten the clevis screw, using your fingers or a pair of pliers, or check that the . Once the clevis and pull rod are connected, you can adjust the lever:
Lift the lever as far as it will go to close the stopper all the way. If the stopper doesn't move, remove the lever and reconnect it to the stopper plate as described in the next section.
Push the pull rod up about two inches until the lever aligns with one of the holes in the clevis.
Insert the lever through one of the holes of a squeeze clamp, then through the hole in the clevis that best aligns with it and finally through other hole of the clamp. Squeeze the clamp and slide it an inch or two along the lever. Release the clamp to anchor the clevis onto the pull rod.
Test the stopper. Pushing the pull rod down should open it and pulling the rod should close it.
The Stopper Is Stuck
When the stopper remains halfway open, the problem is usually gunk in the drain. To clean the drain, you have to remove the stopper:
Disconnect the clevis from the lever.
Unscrew the retaining nut holding the lever to the tailpiece. Remove the lever, then pull the stopper out of the drain. Clear hair and scum from the lever and pull as much as you can out of the drain. If the drain is severely blocked, remove the P-trap and clear the tailpiece with a chopstick.
Reassemble the mechanism by dropping the stopper into the drain, inserting the lever and hooking it into the hole on the end of the stopper plate, which rotated to be nearest to the lever. This is easier to do if you have a helper to rotate the stopper.
Screw the retaining nut onto the tailpiece and tighten it finger-tight. Reconnect the clevis and pull rod, then test the drain by filling the sink, opening the stopper and letting it drain. If the retaining nut leaks, tighten it with adjustable pliers.