A screw loose
This is Jane's 17-85mm lens that developed a fault which meant that it would only work at full aperture. The cost to have it repaired was not worth it so I decided there was nothing to lose trying to fix it myself.
I read that the problem was likely to be a faulty ribbon cable to the iris assembly and there are loads of youtube videos explain how to take the lens to pieces.
This I did and was able to prove that the ribbon cable was indeed faulty. Unfortunately, although I had ordered a new ribbon cable, the fix requires a complete new Iris assembly which I have now ordered online.
I hope I can remember how to reassemble it. Unfortunately there are no videos showing the reverse process. However, I videoed the entire disassembly process so far and will also video my attempts to put it back together again and publish it if it works.
I expect Jane will tell the story about the time I took an iron to bits and there was a pile of screws left over when I finished.