The K-mount system is designed so that the lens aperture is fully opened when the lens is properly mounted. That should apply to any lens with a K-mount. So the first question is, does your lens mount look like the first one pictured in this article?
https://www.pentaxforums.com/forums/pentax-lens-articles/87589-photos-k-m42-m...-k-mounts.html
If it does, you should look through the lens off the camera. The aperture blades should fully open in two ways. With the aperture ring set to f4.5, they'll always be open. They should close a little with each step on the aperture ring and be fully closed at f22 or whatever the highest number is. Then you should be able to move the aperture lever (tab sticking out of the mount) and the blades should open. The lever is spring-loaded and should have little resistance to movement. You should be able to flick it and have the blades snap open and closed, somewhat like a shutter.
When the lens is mounted on the camera, the camera has its own lever that holds the lever on the lens fully open. If that doesn't happen, the lens aperture stays closed and the viewfinder gets pretty dark. You can normally see something, it's just grainy and dark.
Does the lens work at all on the ME Super?