How to Repair a Tub-and-Shower Valve

Pop off the valve cap with the point of a nail file or a similar tool to expose the handle screw. Remove the screw and pull off the handle.

To remove a lever handle, look for a setscrew (a small cap may conceal it as well) and loosen it (it may have a hex or a slotted head).

Remove the escutcheon (cover plate). Depending on the model, you may need to remove other parts between the handle and the valve body. Lay out the parts in order of removal or label them so you can replace them the same way.

If the valve has stop-check valves--large plugs with slotted heads in T-fittings on the hot and cold feeds that lead to the valve-- close these by turning them clockwise. If the valve does not have shutoffs or if they're inaccessible, shut off the hot and cold water to this branch or to the entire house if necessary.

Pull off the U-shaped retainer clip (see illustration). Or use an adjustable or channel-type wrench to remove the nut that locks the cartridge into the valve body.

Grasp the cartridge with locking pliers or a similar tool and pull it straight out (see illustration).

Open a water line momentarily to flush out any dirt in the valve body that might cause a leak. Stuff a dry rag under and around the valve to keep water out of the wall opening.

Clean the cartridge with an old, soft toothbrush and replace the O-ring at the base of the stem. Reinstall to test.

If the problem persists, purchase a cartridge repair kit, which will include the cartridge, a full set of O-rings and grease. Install it according to the manufacturer's instructions.