Although most single handle shower and lavatory valves are now ceramic cartridges, Delta still uses a ball and two washers on some models. For technical support on your ceramic cartridge single handle valve be sure to have the manufacturer and if possible the product number, name, or description and e-mail your question to our retail department. For any ceramic or “plastic” single handle cartridge you will need to replace the entire cartridge and possibly washers that reside below the cartridge. There are many different makes and models and more information would be required. For Delta shower and lavatory valves, this is how to fix them; First you want to remove the handle, the screw is located underneath the button on the handle. After the handle has been taken off there should be a little piece of metal sticking out from a metal housing. You then need to remove the metal housing. It should have a place to grip on to. After the metal housing is off you should be able to see a metal or plastic ball. Remove this ball and under it should be two little washers and springs underneath them. You will need to replace the little washers and springs and possibly need to replace the ball. When putting this assembly back together be sure to follow these instructions: Make sure when putting the ball back in place to align the grove in the ball with the brass pin in the valve body. Also make sure to align the tab on the plastic piece that goes over the ball with the grove in the brass body. Then place the metal cap back on the valve.