Originally Posted by
pacificaslim
If you absolutely have to use it again, then grab a dremel tool with cut-off-wheel and just cut a slot or slots in the round end that fit the screwdriver of your choice, spray liberally with PB Blaster, come back the next day and hold the round end with the screwdriver and loosen the nut off the other side.
Good advice! PB Blaster works better than any other penetrant that I've ever used. I guess rust rules out stainless steel, which has a tendancy to gall.