I had a very difficult one a couple of years ago. I used several cans of PB on it for over a week with no luck. I ended up using heat. With that said be VERY careful with this procedure, any oil, PB, or other release agent you have already tried has to be completely cleaned off. It took quite a bit of heat, make sure its even, and that tap it with a dead blow hammer and off it will come.
Chris
Superior Nights 53C