If this part was stainless on stainless, and you've galled the threads, it's pretty much pooched.
By the condition of the screw, which, despite constant exposure to the elements, is not rusted, I'm guessing the screw and "nut" are stainless.
My guess is a replacement is required for reliablity.
If it isn't going to be reliable, I don't want it on the boat.
Before you decide to go without, there are lots of other styles of backstay adjusters....
Well, yes, but it would appear that, regardless of style, "mid-size boat" backstay adjusters are expensive. There's X amount of load. Whatever style it is has to bear that load. Designing and fabricating hardware to bear that load and, even more difficult, operate
while under that load, results in expense. If you know of a product that will handle the load, can actually be operated under the load, and wouldn't cost an arm and a leg, I'm all eyes. Btw: We're absolutely, positively not
interested in going to a split backstay.
The Admiral is currently of the opinion that if the current backstay adjuster cannot be salvaged, and relatively inexpensively, there'll be no backstay adjuster. As much as it pains me to actually downgrade
the rigging, especially due to my
screw-up, I'm prone to agree. This is getting out of hand. Enough is enough.
Thanks for your comments, Faster. Apologies for the negativity. I'm in rather a black mood this morning.