As additional info maybe, sketch shown is to my BJ8 sensor which I assume is the same on yours. Not totally accurate in terms of dimensions indicated at overall nut and coil (ie: don't recall the securing nut only measuring 3/16" thick), but the appearance of the flared portion of the probe and probe's base is a pretty good sketch representation. Hopefully, someone can post a photo of one. I am hopeful this area is what is giving you most difficulty in removing only. The advice given above about penetrating oil, wiggling, engine warming, should hopefully do it for you. And yes, patience.