Well I would've thought a bit of heat would've done the trick, nice explanation too Morgan! Next on the list is a blunt cold chisel and clubhammer and whack the feck out of it in an anti clockwise direction.Aim to get a bite into the section above the thread and to the side of the square head, the shoulder of the plug. As for worrying about heating and damaging bearings , the heat is unlikely to do any damage, they are usually fitted using higher temps and most bearings fail because of poor lubrication and/or dirty oil. Though if you cooked your alloy housing it may char the oil causing some lumps of crap to form. But you can give it a quick flush before filling it with fresh oil..Good Luck