if it was mine, i'd cut the stud boss in half around the circumference, and lift it off. see how it's attached. embedded with a disc on the stud? replace the stud, and then epoxy the top half of the stud boss back onto the bottom half. i'd use my dremel tool, with the mini circular saw blade on it. it's already broken off, so you aren't going to lose anything by removing the bottom half.