Yeah, always start with a welded nut, I would have used a washer under on that one as well, the extractors are lower success percentage with higher potential for catastrophe, eg, break an extractor in the hole.
You’re meant to swear at it - a lot as well...
mig welder and a nut works great for this kind of thing.
Thanks! Yes, I wasn't aware of the welder/nut method at the time - that would certainly work well, assuming correct size nut, and quality weld. Next sheared bolt I'll try it out.