Most of the time, the 9 month molt is subtle, with missing neck and butt feathers, but last year, I had some that age go through a much longer than normal one, complete with big time weight loss. It was really weird.
They do go through a nine month mini-molt, but it doesn't usually last that long. If you've dusted them for mites/lice, I'd give them canned salmon a couple times a week for a protein punch. Bare bottoms are normal in a molt and they often appear red. I have one hen who is getting over her molt...