Not a collector but I recently came across a Bluegrass 8" adjustable. The adjuster was frozen to the screw. I had to smack the adjuster with a chisel to break it free of the screw and was able to save the screw by taking it out very carefully. (This was after a couple days soaking in vinegar and weeks left in the parts washer solvent tank). I replaced the adjuster with some brand X item - the plating doesn't match, the adjuster seems to be nickel plated. The adjuster was a wee bit larger than the original and I had to file the opening for the adjuster to spin freely. So it's a hack job but it now works well.
If you're interested I'll send a photo.
The middle wrench in the photo resembles an old Snap-On or Blue-Point, doesn't it?
Edit- the chrome is better than it looks in photo - appears dull