
...it won't unscrew! It just turns (with some friction) as if the nut underneath is is loose in its socket or something, any ideas on how I can remove it? The screw is one of two holding the plastic cover in place.
The other screw is fine.
I've tried wedging a flat head in between the washer and nut itself and then turning it was the socket wrench but it won't give

I had it off the other week when I was re-fitting the cover as it was on incorrectly and screwed it back up just fine, not too tight either (I think).
Arse!