Dan, do you see the two center bars going across and attaching to the upright pump frame bars. Just below the computer. You will note that there is a latch assembly attached to the cross bar. In the picture you can see the front view and the rear view of the bar. If you look at the back of the door in the center is a brace that goes across and is placed at the same height as the cross bar on the pump frame. There is a slot in the door brace that accepts the latch from the cross bar. If you turn the latch from the back side and line up the latch so that it will fit into the slot in the brace as you are closing the door. Once the latch fits into the slot turn the lever further and it will lock the door in the closed position. Hope the foregoing makes sense.
