You will need to replace the cartridge. It is a 1225 Moen cartridge which you can get at any hardware store Home Depot or plumbing supply. A brass cartridge is also made but it costs more and is no better than the plastic cartridge. The tools you need.are silicone grease or heat proof grease, a phillips screwdriver, pliers, a 34" copper cleaning brush, and a small flat screwdriver or an awl. The water to the house must be shut off before you remove the cartridge. Open the valve to bleed the water pressure. Turn the handle so it is in the neutral position between hot and cold. This will make it easier to orient the cartridge when you replace it. To access the cartridge, you must first remove the handle. In order to remove the handle use the awl or screwdriver(or a knife) to pry off the cap on the handle. Once the cap is removed use a Phillips screwdriver to remove the screw. Now the handle can be pulled straight off. Pull off the chrome stopp tube that encloses the cartridge. No pliers needed, just pull it straight off. The brass spindle in the middle of the cartridge has a notch on one side or the other. Take note if this notch is up or down because that is how you are going to install the new cartridge. Keep in mind that if you install the cartridge improperly where hot and cold are reversed, you can simply remove the handle and spin the brass spindle in the cartridge 180°. There is a horseshoe shaped retainer clip that keeps the cartridge in place. Use your small screwdriver or awl to pry upward on the retainer clip to remove it. A white plastic cartridge removal tool comes with your cartridge. Place it onto the spindle and turn back and forth back and forth to loosen the cartridge. Now you can take your pliers, grab the brass spindle firmly, and pull straight back towards you. If this is a really old valve it might not want to come out. Keep trying, but if it doesn't work you will need to purchase the cartridge removal tool. Be aware that there are two different types, one for the posi-temp, and one for the basic cartridge that you have. It is similar to a hub pulling tool used for cars. Back the nut on the tool up all the way towards the T-handle and back the screw all the way out. Now place the tool onto the brass spindle of the cartridge, and turn the screw until you can't anymore. Take the T handle, turn back and forth to loosen the cartridge. Now you can advance the nut. Use your pliers on the nut if it is too difficult to turn with your hand. The next step is something that I do to ensure better performance and a longer lifetime of the new cartridge. Take a three-quarter inch copper cleaning brush and turning it clockwise push it into the housing of the cartridge. Never turn the brush counterclockwise. As you remove it from the housing turn it clockwise. Now the lines must be flushed to get any debris out of the cartridge housing. Turn on the water main for the count of three seconds and then turn it off. Take some silicone grease or heatproof grease and rub it on the inside of the housing Now you are ready to install your new cartridge. As I said before, take note of the notch on the cartridge. The two tabs on the end of the cartridge must align vertically. Push the cartridge all the way in and reinstall your retainer clip. If the clip does not go all the way in the two tabs on the cartridge may not be aligned properly. Use your cartridge removal tool or the plastic piece that came with the cartridge to line these tabs. If they are not exactly vertical the clip may not go on. If the cartridge is not pushed in all the way to clip may not go on. But the stop tube and handle back on and you are done