This is where I own up to it all being my fault by discovering I’d missed out the 1.8mm spacer required behind the cassette. Idiot.
Reassembled it all, cassette no longer wobbles, obviously. Presumably that play was what caused the cassette to bite into the freehub splines at an angle.
My new problem is now I’ve put it all back together, the freehub barely goes backwards, making riding impossible. Is this because I’ve packed the ratchets with too much grease? As it’s all a press fit there’s nowhere to loosen the freehub off (the bearing are still running smoothly). Now the cassette slides on and off like it should, I can’t use it to lever the freehub off and even gripping it with the big wrench doesn’t persuade it to come off.
How do you remove the freehub now?