I am determined to finish this sweater.
I have attacked the sleeve not fotting issue by running a line of stitches on the sewing machine and cutting away the excess fabric in the armhole and sleeve cap.
Almost ready to just seam the sleeve on by machine. But that's impossible to rip. So I will try again by mattress stitching by hand.
The third picture is the other sleeve. The lump at the top is what the sweater surgery hopefully will remove. Most of the puffiness seems to be steeking that should have folded in nicely instead of bunching up.
Sometimes you learn by study. Sometimes by mistakes. (I prefer method 1.)