[paul ron]

Those screws are for leveling the lens, not holding it in place. They were popular in the 60's

Those 2 screws at teh very back only hold the spring in place n are not lens levelers at all. Once the 2 screws are out the metal angle comes out n behid that is the spring that is only a tensioner for the lens board.

The 2 knobs are for holding the lens board nice n tight to the mount reducing light leaking, some even had a strip of light seal foam.

The lens is leveled by the entire stage.

.