Things You'll Need
Small flathead screwdriver
When replacing the Moen cartridge on your sink or shower faucet, you will need to first remove the retaining clip. A stuck Moen cartridge is a sure sign that the clip is still securing the cartridge to the cartridge body. The clip keeps the cartridge from floating or turning around inside the body while you are operating the faucet. Depending upon the type of cartridge you have, you may have one or two retainer clips to remove from the cartridge.
Inspect the cartridge to see if it has one or two retaining clips. There will be one near the base of the cartridge, and some models will have a clip toward the handle end around the stem.
Grab the edge of the retainer clip with a pair of needle-nose pliers. Squeeze hard on the pliers' handles to maintain a good grip on the retainer clip. Slowly pull the clip straight out of the cartridge.
Insert a small flathead screwdriver between the bottom of the clip and the cartridge if you cannot grasp the clip with pliers. Pry the clip out far enough that you can get a firm hold with the pliers. Pull the clip straight out of the cartridge.
Pull the clip out slowly to prevent accidentally breaking one of the legs on the clip. Although you will still be able to remove the cartridge with a broken clip leg inside, it will be a bit more difficult.
Do not reuse clips when installing a new cartridge. The new cartridge will come with new retainer clips.