Repair your Moen faucet with a new cartridge replacement if the unit leaks or performs poorly. This replacement installs a brand new set of valves in the faucet to upgrade performance levels and update the device. It's a job for anyone who has limited or average experience conducting home repairs and it should only take about a half hour. The most important part of the project is finding the right replacement cartridge for your make and model of Moen facuet.
Turn off the water by shutting the water valves to the faucet under the sink.
Take off the small hot/cold button on the front of the faucet to expose the set screw. If there is no button, just locate the set screw and remove it. Unscrew the set screw with an Allen wrench and slide the handle off the faucet.
Take the dome nut off of the faucet. This is a large, cylindrical piece that slides over the faucet head. Remove the base of the faucet (on spray handle models) completely to access the cartridge nut. Once you see the cartridge nut, remove it by turning it counter-clockwise. Slide the cartridge out and replace it with a brand new one.
Replace the cartridge nut and tighten it by hand to secure the cartridge in place. Replace the handle base (on spray models) and then replace the dome. On single handle faucets, you will simply replace the dome nut. Then slide the handle onto the stem of the cartridge and align it so the lever faces forward. Tighten the Allen screw with the Allen wrench to hold it in place securely.