Some more information on how the dots work:
If you look at the bottom right of the two good units you will see a dial. This dial can be set to Red, Green, or Blue. If you look above (to the right of in the photo) the ground glass you will see three Red dots and two Green and Blue ones. The sliding back will stop and lock at the color of dot that is selected in the dial.
When shooting just a single frame its best to use the middle red dot (which is the only one that lines up with the smaller screen unit).
When shooting a 3-frame stitched panorama. All you have to do is take a shot at each of the three red dots and combine in post.
2-Frame Panos can be shot with the green and blue dial settings.
Panos can be shot with the back in the portrait or landscape configuration. Changing the orientation is as simple as squeezing the blue back release button to remove the back (while the back is still connected to the adapter plate) then rotating the back 90 degrees and reinserting it into the flex adapter again by using the blue release.