Here's the farm fix - wipe off any oil or grease (anything flamable) then hold a lighter to it, not enough to set anything on fire but just enough to make the metal expand a bit. Then give it a sharp whack with a mallet, not up or down but just to make it twist. Once it's moved even just a little it will be easier for the oil to get in between the parts and you'll be able to wiggle it to where you need.