Taking my cases apart today on my 750F2 one of the 5mm bolts at the front of the engine broke off leaving only about 3mm of the bolt above the threaded hole. Tried some wd40 with multi grips, then a heat gun with multi grips but it did not feel like the broken bit was going to undo without ruining the 3mm proud bit. I have never used an eazy out with success, usually end up with a broken easyout in the centre as well as the broken bolt so gave up on it for the day.
Wondering how much you can heat up the engine case in a local area without it warping the case?. The heat gun I have could heat the case a lot hotter than I had it today.