Mir-47k servicing?

[BigMackCam]

Hi folks. I just received an absolutely immaculate Mir-47K which is optically and cosmetically perfect. The only problem is, it has a lazy aperture.

Has anyone taken one of these apart? If so, can you suggest the best order in which to work, or offer any tips?

Any help would be very much appreciated!

Thanks in advance

[Lightshow]

The lazy aperture, as in one blade is out of place? That is caused by few things, sloppy tolerances, wear of the aperture blade pin, or wear of the slot the pin slides in, in all cases it's a very tiny error, and fixing it will require very exacting work.
Errors are magnified by the ratio of the distance between the pins and the length of the blade.

Since the lens looks like it's new, its probably a tolerance issue, I had a Mir 20M that was also stricken with a lazy bladeyou can't really see its effects unless you have bokeh balls, which is not a common situation with a 20mm lens.

[BigMackCam]

I should have been a bit more specific :p By "lazy", I actually meant somewhat "sticky" . If I set the lens to f/22, then move the aperture lever back and forth to close and open it respectively, it will often get stuck part-way open. It looks like there's a little lubricant on the blades that might be causing this, though nothing like so bad as some lenses I've bought and serviced. I suspect it may be a combination of that, plus congealed grease and/or a weakened spring in the stop-down mechanism.

I'll take the mount off the lens today and have a look. If it's just the stop-down mechanism that needs freeing up, I doubt it will require much work - just a little cleaning and light lubrication, hopefully. I may be able to partially clean the aperture blades in situ with a swab and mineral spirits, too. I'd like to avoid a complete disassembly if at all possible.