f3.5 = not working
f4 = f3.5
f5.6 = f5.6
When the aperture ring is set to 3.5, it's fully open, so you probably won't see the blades at all, so I would say 3.5 is working.
At f/4, it'll be the first sign of the blades, so if you don't see the blades when the ring is turned to f/4, then it's not working. If you see blades, it's probably working just fine.
If f/5.6, as you say, is f/5.6, then assuming you see blades at f/4, and no blades at f/3.5, then it's safe to say the lens is working fine.
The lens has a total of 8 stops - f/3.5, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32.
If you start at one end, you should be able to count 7 clicks, and see blade movement 7 times (including f/3.5 where the blades disappear, or first appear, depending upon which side you started from).
My guess, based on the info I quoted, is that the lens is working fine.