When swapping seats I broke the rear outer bolt of the drivers side seat. I tried to drill it out with some cobalt bits. The thin ones break and are hard or impossible to remove. The fat one does nothing even if I lay on the drill. I bought some reverse bit extractors. I can't get them into the screw. I hammer them down. Or try to make a small hole for them. But they slip and do not grab. Any tips? I don't have acetylene but the bolt can't be seen from beneath the truck.