To dismantle the Trend A tap you will need to remove the red/blue inserts on the end of the handle and undo the screw that is underneath ( NOTE on some Trend taps the handle itself will unscrew). Remove the casing and undo the large nut that secures the cartridge. You may achieve this with thin nosed pliers if a suitable socket spanner is not available. the cartridge can then be removed. the replacement cartridge is our part 149288.