The stiffness in the aperture ring isn't the blades. (If it was, they would buckle in an instant!) The ring itself is a very tight fit on the lens barrel, same as with the Summar and collapsible Summicron. There has to be clean light grease in there.
As for internal cleaning, I would recommend ONLY trying this with an uncoated Summitar. The coating on a coated Summitar is very soft on the outside, and more so inside. You need to know the right chemicals to clean the inside, and even then the coating may have to be cleaned off with the haze! (I speak from experience, messing up a Summicron.)
To remove the aperture ring, you would have to remove the inner barrel from the collapsing barrel. Remove the setscrew(s) holding the rear bayonet ring. Pull the optical unit. Then remove the two screws on the aperture ring, remove it, and clean and grease the mating surfaces.
Only if things are really bad do you want to consider removing the iris blades. If that rotating ring is stiff in the lens, you're stuck, but expect to have an "interesting" time putting the blades back.
