Interesting vise, how do you bolt it to a work bench? Neat jaw design. Added to Spreadsheet.
The screw that is loose on the first picture is a cosmetic cover screw which allows one to access the real screws that bolt the bottom plate to the workbench. The handle actually goes to the left side. Setting the proper "tightness" happens with a big center bolt only reachable from the bottom that needs to be pinned in place. Shims are required since there are only 180° settings for the bolt.
I used to have a 2" before and I still have a 2.5" or so that is a monday model with some "issues". I also rescued a ~4" recently which is different as the guides for the dynamic jaws are round, which was probably not easy to machine. You probably saw that on my instagram.
Here is a catalog picture (dutch probably, but captions on the text are german) from somewhere, note the revised, normal swivel lock mechanism.









