Bob, you ever try heating up the exhaust around the bung to see if it would expand and allow for the O2 to be removed from it's original position?

The placement of the O2s is crucial. The new O2 is placed too far downstream. Thats prolly the cause for your Bank 1 condition.

We have talked about the MAF and since there were no changes after you cleaned it, we can rule that out.

My mind keeps on going back to the placement of the O2. I say wrench the stuck one out, put a plug in the second hole (good place for a future Wideband), and put new O2 back upstream in the original location.