I tried the MIG/Nut trick with no luck. I think there is something wrong with the studs themselves (defect of sort). A couple of them had enough of the shank left for 2 nuts, and I attempted to tighten them against each other in order to back out the stud. The stud snapped as soon as I barely tightened the nuts (maybe 5 ft/lbs). The hardened left-hand drill bit won't even scratch them, and the Kolbalt bit cut about 1/16in then quit.