Disassembling Elmar 90mm (9cm) F4

Hi,

I bought a M-mount Elmar 90mm F4 lens. The lens has a trouble in apertures. So, I tried disassemble the lens to fix the trouble. I found this page about the disassembling of the lens.
https://www.photrio.com/forum/threads/loose-aperture-blades-on-leica-elmar-90mm.118879/
I followed it. However, I noticed my lens is little bit different from one in the above page. I could unscrew the top plate and remove first lens element. This is the disassembled lens.

But I could not go to next. Any parts could not be disassembled. Then, I tried disassembling from bottom side. I could unscrew the bottom lens element, but then I could not go next. This is the bottom side.


How can I reach the aperture blades? The lens barrel is seemed one piece. Anyone success disassembling the lens?

It looks like the black ring in the pic is threaded, Standard right hand thread.
A rubber stopper that fits inside the barrel and possibly a drop of penetrating oil on the threads may do it.
Use the penetrating oil ONLY AFTER trying to unscrew it dry.

Replacing the blades is a pretty delicate task so I've used a film can inserted from the back
can help hold them in position while you work.

Thank you for your reply!
I tried to unscrew the black ring, but I could not open it...
I carefully watched the barrel, and I thought the silver one and black one cannot be detachable.
How do you think? The screw hole seems to be connected from black one to silver one.

Try soaking the threads between the black (inner) ring and the silver (outer) ring with Acetone for 5 to 15 minutes then try to unscrew the inner ring again.