Maybe this will help.
https://www.flickr.com/photos/advance-design_parts_co/albums/72157641244124604
The two screws attach to the vertical bracket, then you install the handle screws with the vent pulled full open.
https://www.flickr.com/photos/advance-design_parts_co/12297591924/in/album-72157631868452754/
There is no real adjustment on the springs they just need to be hooked up correctly and unbent (they were eliminated by mid-‘49).
https://www.flickr.com/photos/advance-design_parts_co/12297591924/in/album-72157631868452754/