Install the plastic washer, then the rubber washer ... mind that it is much easier to clean and maintain a universal pop-up sink stopper than it is to work with a more traditional pop-up stopper ...

If a pop-up drain stopper in a sink or bathtub doesn’t work ... You may also need to replace the gasket or washer (or both) ...

Don't let your valuables go down the drain! If your sink plug is stuck, you may need to fix or replace the sink stopper.