VPI VTA Column thumbscrew on my super scoutmaster

Can anybody tell me thread size for the thumb screw that's used in the Classic tonearm VTA column on my Super Scoutmaster rim drive? Right now this thumbscrew is missing and I'm looking for a replacement. I need this thumb screw to lock in the tonearm, vpi recommends this for best performance. Thanks
I would just call VPI and have them send you one or just get the specs. The threads could be metric or SAE, and even if you get that right, you'll need to know the length. If you had another screw you could use to match up to a new one in a store, that's one thing. If not, I wouldn't take a chance without the specs.