Yeah they are a pain lots of old stoves are like that. You either need to peen out the female end to slide over. Or over crimp the male end which I usually hammer back out after it is in. There is also.an adapter that works. The picture is of the 6" version but you can figure it out from that8inch female wont go over to fit...8 inch male doesnt fit in.What am i missing here im pulling my hair out.
Your pipes appear to all be backwards. Condensate will run outside of the joints and possibly onto stove top at stove collar. Crimped, male end facing down keeps condensate inside pipe to be consumed by stove.I had the same problem so I made a collar to fit perfectly around stove flue hole