I hate to say it, but you could take one more set of shots. Take a shot of a small point of light surrounded by a dark background, with the light out of focus. Something like a street light at night is good. When the aperture blades are fully retracted (lens wide open), the light should be a perfectly round circle. When the lens is stopped down by any amount, the circle should change to a polygon with one side for each aperture blade. So at f3.5 you should see something like this:
I don't know anything about the 40XS. It might be a lot different than typical lenses because it's so tiny. On a typical lens the fix is not that hard. Here is a photo of a lens (F70-210) with an adjustable aperture lever. Only the mount has been removed here:
The aperture lever is on the right. Two screws are at its base. The holes in the base are slotted, so you can simply loosen the screws and shift the lever a bit each way. Probably a good idea to mark it before unscrewing. It would be really easy if you already knew which way to move the lever and exactly how much. Otherwise you'd have to put the mount back on and test. The lens in the photo makes that process extremely tedious, with each contact having a spring, contact and insulator, all just about to fall or jump. Newer lenses are often easier. At least you won't need to worry about the aperture ring. You'll want a set of JIS screwdrivers for this.