Remove the leaaver by flicking out the red/blue insert, with a 2.5 mm alan key slacken the clamping screw. remove the operating leaver.
At this point make sure that the water supply is OFF.
Now unscrew the chrome besil hiding the inner works.With a large movable spanner unscrew the brass clamping nut and remove.
The cartridge can now be removed bu taking hold of the operating leaver and lifting it out.
This part is not repairable and a new one must be fitted in its place.
Ossy, January 2011