I ' ve always had good luck on this sort of problem by taking a nut the same ID as he OD of the bolt that was broken off and positioning it over the top of the broken bolt and then basicly welding the nut to the end of the brokenn bolt, as long as the easy out didn't get out past the OD of the bolt the heat from the welding process is usually enough to loosen the stuck bolt, and with the new nut welded to it you now have a way to turn it too!
