I set the troublesome sleeve aside and knit another on 7mm needles, a size smaller. The new sleeve turned out great, so I knit another just like it. Then I cast on for the body: I've just finished the ribbing.
I have never knit a sweater in the round before, apart from Green Silk Frustration, which is a top-down number. This one is bottom-up and I am loving it! Firstly, no seams to sew! A complete sweater is coming off my needles! Secondly, it is hilariously like knitting a large sock. Wish me luck for a speedy finish.