replacing masthead wire

[Brion Toss]

Hello,
Those wires were most likely installed before the mast pieces were glued together. They usually run in very tight spaces, especially at the entry and exit points. And at these points you will find a generous amount of adhesive sealant, to keep water out. You might -- only might -- be able to hole-saw around the wires, and find that the parts in side will run.
Fair leads,
Brion Toss