does this chimney look blocked???

I'll loan you my 7 1/2 inch barrel .44 magnum and hot loads. That looks like the easiest way from here on out. You will have to supply your own goggles and ear plugs.

That actually looks a lot like my chimney did in 1989. My wife was hurt in a car accident and my mother-in-law and father-in-law came up to take care of her while I was at work. One day I came home and the FIL said "Boy that stove burns a lot longer when I put those wet logs from the wood pile in it. I asked how long he had been doing that. "About a week."

I gave them fifty bucks and told them to go have a nice dinner for helping so much. The minute they cleared the driveway I was headed for the roof. The 12 X 8 chimney looked like that one in your picture except for about a two inch hole in the middle. I smacked three trash bags full of crap out of it before they got back. And hauled all of the wet wood back out into the woods and hid it.

All I can figure is that the slow smoldering burn combined with the mosture cooling the flue caused everything that went up that chimney to stick to the flue tiles. Luckily it was mostly ash.

I haven't seen it again and don't want to.