ATF/Acetone.
A machinist magazine did a test of a pile of different penetrating oil products.
ATF/Acetone beat them all, including Kroil.
Soak that puppy, try to keep it ait tight, acetone will evaporate off.
You could maybe get a jump by heating it up a bit before you soak it.
The EZ-out thing?
Last resort before a hacksaw.
