there are bits that will drill out broken extractors and taps commonly called rescue bits..
Broken Screw Extractor Removal Tool by Rescue Bit 1/8"
other options;
weld a nut through the inside to the broken stud.. let cool and should come right out..
call around to see if you can get someone out with a portable EDM on a mag base..
depending on the cause of the bolt to break, whether it's thread bound or the head popped from friction on the crank, might be able to chisel it out with a sharp edge and some patience..
could also try grinding it out with a die grinder and a diamond burr.. and of course, lots of patience..
that's what this whole drawer is for, good luck!
