I bought an older Presentation 3000 vise. I've cleaned, lubed and got it nice. However, I think it's set-up right handed and I'm not.

At the end of the shaft it has two knurled knobs with a brass handle between them. When rotating the shaft clockwise the brass moves the shaft, but when you move CCW the shaft doesn't turn. Similar to a rachet for a socket.

Does anyone know how to reverse the direction?

I sent Renzetti a note last week, no response.