If it's isolated and small pieces of stuff, don't even bother with sandpaper, get out a good sharp razor blade and carefully slice off the stuff. You must be careful about cutting into the threads, but even if you nick one or two or three, the epoxy is probably going to hold the guide just fine. Forgot to add the obvious, re-coat with a coat or two as required to finish up.
I've had to cut out knats, flys, dog hair, you name it and I always just get out my trusty supply of razor blades. Good luck and just who are you calling amatuers
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