To replace a Moen shower cartridge, turn off the main water supply to the shower at the shutoff valve. Remove the faucet’s handle, shower plate and the old shower cartridge. Install the replacement shower cartridge and ensure it is firmly held in place.
You need a Philips-head screwdriver, shower stem socket, flat-head screwdriver and pliers to carry out the task. Using a Philips-head screwdriver, remove the screws retaining the faucet’s handle and then pull off the handle, away from the faucet valve. Remove the shower plate by unscrewing the screw holding it in place and then pull it from the wall.
Unscrew the nut holding the faucet’s valve by inserting the shower stem socket via the shower wall onto the nut. Turn the nut counter-clockwise to remove it. Hold the old shower cartridge at the tip using a pair of pliers and then remove it from the wall. Insert the new shower cartridge and tighten its screws to ensure it is tightly held in place.
Place the shower plate back on its original placement and tighten the screws retaining it, using the Philips-head screwdriver. Slide in the faucet handle and tighten the retaining screw at the center of the handle. Insert the decorative cap covering the handle, and then turn on the water supply.