I have (now 2) nice, 20+ year old lenses, one of which which I know had never been opened.
Yet, when the aperture it stopped all the way down, the imprint of oil is visible on the blades - and the little spring isn’t strong enough to even rotate the tab alone, so it had no chance with a sticky aperture (I have the rear assembly soaking in rubbing alcohol at the moment.
So - how did the oil get in there? Where do I get 00 and 000 phillips screwdrivers which can develop 2-4 ft=lbs of torque without deforming?, and what is my best way to clean and lube the blades should I ever get to them?
The oil typically comes from the focus helicoids, although I seem to remember it can also come from some sort of offgassing of lens coatings.
Rubbing alcohol is not what you want for lens cleaning. Get naptha (Zippo lighter fluid available where tobacco is sold.)
I prefer JIS screwdrivers for working on lenses. You probably only need a 0 and 00 since the screwdrivers are very pointy and work well on smaller screws than you might expect.
When you talk about “ft/lbs of torque” I wonder if you are encountering screws that are locked in place. Some manufacturers put a drop of lacquer on the screws to hold them in place. You can dissolve this by placing a drop of acetone on the screws.
You can also just break it mechanically if you have a good screwdriver, but acetone would be best practice.
Unless you really don’t care about this lens, I would recommend bringing it to a professional. You can badly mis-align a lens by taking it apart, and without optical alignment equipment, you might significantly reduce it’s performance.
Unless you have some experience with this-----or really have a high mechanical aptitude with fine detail work----I wouldn’t touch it, especially if the lens has some real value.