I'm no pro but I will give it my two cents. You may need to be a little creative to pull out an old gaff. Without seeing it, you may be able to use a razor knife to remove the old epoxy and winding if that is how it was built, maybe use a bit of heat from a torch without ruining it and catching it on fire. Even a hack saw or dremel. Then to replace it, attach the new one with tuna or parachute cord and epoxy or any other proven method. I've recently completed one from an old Star rod that came out decent.
Do you have any pictures of the one you just finished? Did you use a gaff hook that was 'pointed' on the none hook end?
I will try using a little heat and razor knife to remove; the gaff is glass and it was definitely wrapped or sort of appears to be some kind of tape? But then its expoxied just like you are describing.