You can run it the way it is,if it broke off any higher than that it would be bad.You can braze it with a torch,I would leave the bolt in there & just braze the bottom piece back on it,if you wanted to weld it with electric ,you need a nickle rod & v-grind all along the area to be welded & then pre-heat both sides or else you risk having it crack when it cools.Also clamp it while welding or brazing so it doesn't move.