[lakeshore]

When resurrecting my M series lenses, I discovered that my M 20 mm f4 and M 35 mm f2 lenses have "sticky aperture" issues. My local camera store wants $100 to $150 "approximately" to repair each lens.

I've looked at the material available on this forum and have decided to try and repair them myself.

Is it possible to fix this problem by only opening the rear of the lens? There is no visible oil on either side of the aperture blades or anywhere else.
Is it essential to use JIS screw drivers or just recommended?
What solvent should I use to clean the mechanism?

Any other words of wisdom from those who have actually done this type of repair?

Thanks.