Tubing nuts often seize between the tube and the nut. IMO the anti-seize needs to go on the tube, slide the nut back out it on the tube and slide the nut forward. Fill the void between the nut and the tube with penetrating oil repeatedly. My preference is Kroil, PB Blaster or Liquid Wrench. Notice what isn't listed...???

Graham keep at it!!! Look up and consider using electrolysis bath rust removal. You could put the entire rotor in the bath to help break things loose. I've had amazing results.

Good luck!!!

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