Sooo… I’ve popped into the garage and on the shelf at the back I found an easyout kit that I must have bought years ago and never got to use. It has an M3/M6 ‘screw’ 🙂
I also found a tapping set that my father gave to me years ago. It just happens to have an M4/0.7 tap (or is it a die – I forget which is which). Hopefully I shouldn’t need it.
As for tightness… well, I didn’t *think* I’d put it in that tight, it certainly didn’t feel at the limit I was just turning and heard a ‘ping’ sound. Uh oh… I know what I did wrong. Tightened on side too much before doing the other and so put massive pressure on the second bolt. Done it before and broke the clamp. In future I WILL do this more slowly.
Right, I’m going to go and have some fun with the easyout. The head is square… now where to find something that might hold that tightly.