The small screw is a “ set “ screw for the larger main screw. At the front of your vise behind the “ meatball” there is a cast washer that as been split in half by design. With a screw driver, you’ll need to in thread that washer( which will come apart once removed) and take out the smaller...
Picked up this vise in Massachusetts yesterday. It came out of an old garage that sat vacant since 1991! Found a date code that looks to be 10/43.
Love this forum…
Matt