Removing Bristan basin mixer tap cartridge

I am trying to replace the cartridge in our basin Bristan mixer tap. I removed the tap lever and the large nut underneath but found the cartridge would not lift out. I then used pliers to get a better grip but then part of the cartridge came away leaving the bottom part in place (see photos).

I have tried WD40 and Limescale remover to see if it will losen it but still this bottom part will not move.

Has anyone got any suggestions? I am trying to lift it out with long nosed pliers. Do I need to rotate it? II could simply try and reassemble the old one, if all else fails, but not sure how the pieces fit together.

I put a screwdriver in the side and gently lever it over till it breaks the suction on the bottom
o rings.Bob

Bob,

Thanks for your suggestion. At first it still would not budge. Then I gave it a dose of Limescale remover gel plus WD40 for good measure. Next day it moved then popped out. I have since fitted a new cartridge and all is well.

Thanks for your help.

Chris