[LS short box]

So here's my .02 on drilling out any bad bolt. If the head twists off and it's a bit above the surface take a grinder and grind the bolt so it's completely flat. If its a small bolt like a 10-24 or 1/4-20 get small diameter center punch and sharpen it to a needle point. Then the best you can center punch the bolt right in the center of the bolt. If your first try is a bit off center just do it again make the punch mark heavier so the drill bit doesn't walk. Start with a really sharp 9/32" bit and drill all the way thru the bolt. Then drill the bolt with a 5/32" bit and the final size drill bit is 13/64". If you center punched correctly the 13/64 drill bit (or #7 drill bit) is the tap size for a 1/4-20 bolt. Re-tap the hole. Even if its a bit off you should be OK.
Good luck.