Mea culpa - I had introduced windsurfer masts to Matt for Mizzen masts and gaff yards, but maybe did not tell him how to reinforce them.
Two ways how you can do your repair:
1., take out the foot plug, and insert an inner plug turned from mahogany and push that up inside the mast to where the fairlead screws are to get new grip,
or,
2., simply use some "Fischer FU 6x35mm" nylon plugs, and follow the instructions on the box, or on Youtube.
C.
P.S.
And, I forgot to mention this time, but this applies to each and every fitting to be screwed down on carbon,: All contact areas -both of the fitting itself and of the carbon- must be primed with nitro solvent, best after some sanding, and the fitting and screws must then be set in Sikaflex or Pantera bonding. CR