A few months ago, I was about to tinker with the horn height on my BC-34. Unfortunately, I was a little over-enthusiastic with the wrench, and broke off the bolt pretty much flush with the casting. I tried a broken bolt extractor; but, to my great chagrin, that broke off as well, and is now embedded in the broken bolt.
I have tried some of the hardest bits i could find, to see if I could drill into that, but to no effect. I did purchase a diamond masonry bit, but have not as yet dared to use it.
Is this a hopeless case?

Bill