Hi everyone,
I'm looking for some advice on how to get the mixer handle off. I've taken the internal screw off using an Allen key but the tap seems stuck on the cartridge. I've sprayed WD40 on the inside a few times and tried wriggling it but it won't budge.
I'm hoping to eventually stop it from leaking by replacing the cartridge.
Any thoughts please?

The stuck mixer

The removed internal screw