Dismantling Mixer Tap to Fix Leak

[PeteM79]

I have a 4 year old B&Q (Cooke & Lewis) mixer tap.

There is a small leak from the middle of the tap. I'm quite handy and thought it was probably a washer, so I attempted to dismantle it to investigate.

However I can't remove the last moving, circular part (see pics). And this is the part that is actually leaking. It doesn't appear to unscrew. I removed the grub screw behind.#

Any ideas on how to remove this and fix the leak?

 

[footprints]

Chances are it does unscrew or twist out but stuck with scale try wrapping in rag and soaking in white vinegar overnight to dissolve scale.

 

[PeteM79]

Thanks. It's obviously meant to move and it does. But I can't seem to figure out how it comes out. But I'll give your idea a go.