I have not tackled a loose aperture problem before; I have had (only) one lens with that problem, an otherwise MINT Nikkor 5cm F1.4 for the SP, and sent it to Essex. The repair cost me $80, the lens came back like new.
For a chrome 9cm F4 Elmar, I would have a repair shop do the work. While they are in it they will clean any haze. If this is a case of "it is not going to ever be repaired", there are some repair books out there that show getting into lenses to this level. Books by Tomosey are helpful, but practice on some junk lenses first.
Right now I am working on the "basket case" cheaply attained cameras and lenses. Joe's Canon F1.8 was one. The two Canonet's that I got from Rob worked out. I am going to practice on some old Wollensak lenses; they were easy to get to the blades.