Before turning lens over, insert a tapered soft rod into the open iris. (I used the rubber handle of a medium sized screwdriver). Turn lens over (photo). Wiggle handle until iris is free.
Carefully withdraw handle from below and you will have the iris in one piece.
Note excess lubricant near the helicoid drive gear. Wipe off all excess lubricant that is
present around helicoid, as it can work it's way into the lens iris.
This one had an oily iris.
This is one of the original 1985 Maxxum lenses with the central helicoid a beautifully machined alloy casting.
The lens mount boss ring is also a heavy machined casting. The outer helicoid and integral drive ring is plastic.