Hi Buze! First of all, un grand merci! If only the net had tuturials for all lenses (or at least lens families), it would be great!
I just got a much older brother of your lens (according to the serial number) from ebay. It was advertised as having a stuck diaphragm, and your tutorial had convinced me that this would be a fun thing to solve - and of course the lens cost near to nothing.
Some notes, some problems specific to my little lens.
- You might change the order of two things in your tutorial: the warning about removing the little ball  and the instruction to remove .
- Note that the spring under ball  may actually be loose as well... and it's black, so it's easy to lose. In my case the little spring came out, and I put it aside together with the ball.
- Next, I found the problem with my lens, see picture:
Not the diaphragm was stuck! In fact, it was working perfectly and smoothly! But somebody put a lot of glue (see arrow) between the aperture setting ring  and the focusing barrel . So, I had to clean away the glue. I used quite some force - noting that the area around the glue was already very scratched. See result below.
Now, the part of aperture ring  where the glue was, is supposed to interact with the part of the focusing barrel  shown in the following picture, in order to create the click-stops of the diaphragm.
Actually, it doesn't! I think there should be a little spring and ball in the hole that was filled with glue. How is that in your lens Buze? You did not mention it - am I mistaken about the ball that should be there? Does your aperture ring "click" into the stops somehow?
Anyway, I put it back together, and the aperture ring is turning again, more smoothly than ever (too smooth...). There seems to be some small problem with the focusing barrel - I think it is not perfectly round anymore. But after reassembly and some fresh grease it is in good shape again!
Time for my little Tessar to return the favour to his friend who documented the work
Tessar 2.8/50 @ f16 on Canon 20D, 8s at 200 ISO.