Solved!!
It was the original OEM bolt that came with the unit, so by specs it would be grade 8.
I drilled a half inch hole in the cowling and my plumber who was here thawing our sewage drain put a long punch through the hole, and he reefed on that sucker with his heavy ball peen hammer several...
The keyword is 'most'! This morning, with a deck screw (i.e. pointed thing) I was able to locate the bolt, it is exactly where I thought. I could feel around the edges and the bump in the middle. Pounding at it did me no good.
BUT I now managed to get the fan out the rest of the way!! It was...
I did manage to snap some shots before we left home in the morning as the tractor is by the front porch and the light comes on. But it was -25C (-41C with wind chill, and -40C = -40F so you know what I'm talking about!) and my hands froze up in the time it took to do it and I had to go in and...