First, thank all of you for your amazing input. The good thing is that because of past attempts, the aggressive attack has created a natural indentation and so far the penetrating oil is disappearing. I'm going to try to use my dremel bit to increase the slot if possible. But before I do that I will alternate between penetrating oil and soldering iron to get it loosened up as much as possible. Info to follow to all interested. Thank you again.
Carl