Naval jelly is mostly useless. PB blaster seems to be one of the best for freeing up rusted parts. After that I usually break out my oxy/acetylene torch. (I'm used ot working on rusty cars and the "flame wrench" solves a lot of hard problems!) Dont bother with propane. It doesnt put out enough heat. Impact is your next friend, but dont overdo it and damage the end of the tube.

Good luck!

-SP