Accessing the cartridge
 1 - Using a flat-head screwdriver, remove the plastic cover, then remove the screw with a 3 mm Allen key.
 2 - Dismantle the lever by pulling upwards, then remove the cap.
 3 - Unscrew the nut with a large, 32 mm socket wrench and pull the cartridge firmly towards yourself. If necessary, replace the lever to make this easier.
 4 - Make sure there are no seals or foreign objects in the mixer body.
 5 - Then install the new cartridge into the mixer body, positioning the two tabs on the cartridge into place.
 6 - Screw the large nut back with moderate pressure using the 32 mm socket wrench. Replace the cap.
 7 - Replace the lever and tighten the screw with the hex key.Finally refit the plastic cover.