Never mind. The last trick in my repertoir worked. I put the hex socket on a breaker bar instead of a ratchet and rocked it back and forth in both directions with as much force as I dared. After about 10 cycles back and forth I heard the first creak. It creaked and groaned so much all the way out that I turned 1/2 turn out and 1/4 back in like tapping threads to try and keep it from locking up on corrosion particles in the threads.