Silversmithing studio in NYC has this ancient device that does not work. I am mechanically inclined and cannot fathom how it could work in its present configuration/condition. Some parts are missing and/or deformed. I searched the internet and can find very little info. I wonder if anyone here can lead me to sources that would enable me to salvage this brake. I do not like to throw things away. Parts? manual? Whatever.

Here are photos, some bad, two good.

Any help welcome.