GNM, you're right. Sadly, these things have crossed my mind too. Seems ashamed, that this cool old piece may be scrap. Something I'm sure the original maker could never have imagined. But, that's the world we now live in, one where everything is disposable because parts are either too costly or unavailable. I was just saying to a friend who's TV "died" that I recall the days when the TV repairman came to your home with a large hip box of tubes and other components and fixed your TV and it was a very small cost compared to buying new. Now, you just throw it away and get a new one at Wally World. Same for every major appliance in your home. I found a reference on another site where someone said back in the day Sears, Roebuck used to carry various sized post vise repair kits that included the replacement screw and thread box for $10-$20. Now wouldn't that be nice! Yeah I know, BOOMER! Guilty as charged.
If I am unable to repair this myself I'll see if my buddy wants it back. If not, I will likely pass it on to someone with the advanced skills and tooling to revive it. As you've said, especially for what I plan to do, dabbling in knife making and small item smithing (think hooks, bottle openers) as gifts for friends and family I probably don't need a post vise. My buddy knew I got a little 66lb Vevor anvil for Christmas and thought I might like the vise and kindly, he gave it to me. Something I appreciate regardless. Thanks for your comments. Hopefully, others will have ideas that might yield a viable solution.