I should have added, to replace the o-rings. Turn off water supply to the faucet. Remove the handle which is held in place with an allen screw. After removing the handle then pull the chrome cover off the cartridge. Do not remove the two screws holding the large round chrome base plate in place. Now remove the brass cover off the cartridge by turning it counterclockwise. Once you have this off use a marker to mark the orientation of the cartridge to the housing. Pull the cartridge out and look on the end and you will see two o-rings. Remove and replace them plus the other o-ring surrounding the cartridge. Push the cartridge back in place exactly like it was originally installed. Put the brass cover back in place and hand tighten. Replace the handle and you are done. I should have added, to replace the o-rings. Turn off water supply to the faucet. Remove the handle which is held in place with an allen screw. After removing the handle then pull the chrome cover off the cartridge. Do not remove the two screws holding the large round chrome base plate in place. Now remove the brass cover off the cartridge by turning it counterclockwise. Once you have this off use a marker to mark the orientation of the cartridge to the housing. Pull the cartridge out and look on the end and you will see two o-rings. Remove and replace them plus the other o-ring surrounding the cartridge. Push the cartridge back in place exactly like it was originally installed. Put the brass cover back in place and hand tighten. Replace the handle and you are done.