Usually you can use an Ezy-Out (or broken bolt extractor), at least I have used them for broken head bolts (fun). I would however wonder if the bleed channel might cause you some trouble when you are drilling the hole for the Ezy-Out. Anyway you will definately need to caliper off to work on it, and you will definately need a new bleeder screw, maybe it time to upgrade to speed-bleeders. Good luck!
