I had hoped this image would be easier to interpret, but here goes. We're looking from the back, with the top of the viewer removed. The top portion, with the viewing lenses, is held in place by a piano hinge running down each side of the case. The "goal posts" are the image guides, with a place for the slide tray on a movable plate below. The method of operation is quite simple. As the handle is brought through 180 degrees rotation from back to front, it operates the cast black lever visible in the open doorway at the back of the viewer. This then lifts a slide out of the tray by raising two round rods, the bases of which are visible as small circles just above the molding which runs through the center of the photo. The slide is held in position as long the operating lever remains to the front.
Returning the lever to its start position lowers the slide back into the tray, and pressing down slightly advances the tray one position. Pressing the lever down multiple times will advance through a corresponding number of frames. As slides are pushed upward, the blank black plate rises up between the goal posts. It serves as a dark slide between images. A fixed mask (not visible here) is located between the slide and the viewing lenses. The operating lever has sufficient mechanical advantage that no springs are required to help lift or return the slides.
Comparing this mechanism to that of the Taxiphote, the Stereodrome uses more simple castings, while the Taxiphote's is all machined brass. Surprisingly, the fragile looking Taxiphote mechanism appears every bit as reliable as the Stereodrome, but must have been more expensive to build.