Hello. I'm brand new to large format. I have a Toyo 45A and a Schneider Apo-Symmar 5.6/120 lens. I just mounted the lens to my 0 copal lens board and I noticed it doesn't sit flat. On closer inspection of the lens there's a screw that protrudes, preventing the lens from sitting flat in the lens board. It's therefore wobbly in the lens board. Can anyone tell me if this is part of the design of the lens. I bought the lens brand new. Here's where the screw is: I unscrew and remove the back lens element, then I remove the ring. Beneath where the ring was, on the bottom of the front lens element, there are 3 silver screws, sunk flush, and the protruding grey screw which sticks out about 1 mm. Thanks a lot.