Before you go welding or drilling for an extractor..... look at the bolt with good light.... most times when they break they will leave about 1 and half p#*^y hairs, if this is the case, grab onto it with some needle nose vise grips and turn it out! If no go there....... just tack a nut onto it! (Just tack it, power on..power off.... DONT melt the gasket)
gig.