Close the isolation valve under the sink with a flat screwdriver. Open the tap to drain what's left.
Flat screwdriverPop off the tap cap, undo the screw and pull the cartridge straight up.
Allen keyOld towelMatch the notches, push it down firmly and refit the screw by hand first.
New cartridgeTurn the water back on slowly and run the tap hot and cold for a minute.
Nice work! Your tap is fixed. Share your result