First you have to remove the main lever/handle. This is done by loostening the allen head setscrew at the pivot point front base of thge handle. Underneath you'll see a collar or nut that is easily removed with a pair of Channel Lock pliers (adjustable) then after marking the front of the valve with a permanent marker(just make a dot) so it is assembled the same way, pry out the valve and repair or replace it, Thank you, Dana.