[B. W.]

With the bolt broken off below the surface it makes it easy to drill dead center. Use a drill bit that fits the hole snugly (is that a word?) For example, for a 3/8" threaded hole a 5/16 fits nice. Just drill enough to spot the center then switch to a smaller bit. The left hand bits work well, sometimes they will "snag" (like drill bits do) & the bolt will screw right out. Good luck!