Hi Wade,
I suspect the lens has been dropped and jammed the helical. If you can get it to rotate at all you may need something like a valve grinding compound to get enough clearance for it to loosen up.
If you're just curious, start at the back and remove stuff that's in the way. watch out for the ball bearing or spring that provides the detent action. When you pull the aperture ring there will be grooves that it rides along. take pitchers or commit it to memory or notes.there will be a spring or two but they're secure. they have loops on the ends and fit over small studs with grooves for the loops.
DON'T DO THE FOLLOWING. Until you're sure the helical is really jammed.
There are two guides for the helical that are screwed in from the back. they're on opposite sides of the lens and held in with two screws each That will allow the helical to unscrew.
FROM THE FRONT.........The decorator ring unscrews CCW. Grip it with the edge of a rubber plug(bathtub stopper?)
under that there are three screws holding the focusing ring on.
I don't remember now exactly but the diaphragm may be removed now. three screws? springs on the lever in the back?
If you're in need of some real training in patience, take the diaphragm assembly apart(snicker) won't take but a minute. Reassembly will take a bit longer. First one might be an hour or two, depends on how steady you are and whether you sneeze on the assembly when it's almost done. Note the direction the blades face when yu take it apart, It doesn't work with them in backwards.
