Talbotti, Mipowdercoater is correct. Drilling out the stud and filling with epoxy will probably be your best bet. Because the top of the stud is no longer flat I don't see you having much success with drilling out the stud. However, you might want to try this. Take a piece of flat steel strip at least 3/8" thick (1/2" would be better) and drill a hole in it the same diameter as your stud. Clamp the steel strip TIGHTLY so that the hole in the strip is directly over what's left of the stud. Then, working SLOWLY AND I MEAN SLOWLY proceed to drill out the stud. You will probably ruin several bits in the process but you may be able to eventually remove the stud. This is a good trick to remember and use anytime you want to drill a hole in anything and the location of the hole has to be exact. Good luck. Ogy