The backstay adjuster is a Ronstan RF718. Google comes up with bupkis for it. Ronstan's site likewise comes up with nothing. So I suspect this device is older than dirt. Maybe I'll try contacting Ronstan. Maybe they have an old-timer there that remembers this thing and even knows where some spare parts are stashed in some dusty corner
.
I'll have pictures later (in case anybody's interested). It's too late for me to fool with editing them down to size right now.
I'm now 99-44/100% certain it's toast. Applied Boe-Shield liberally, then tried to work the thing back-and-forth. If anything: It got
stiffer.
We'll see what things look like after it's off the boat in another couple weeks.
Found out, in additional discussions elsewhere, that stainless-on-stainless is a Very Bad Combination precisely because to the tendency to gall. Better is a combination of stainless and brass. (E.g.: Stainless screw and bronze nut, in this case.)
Jim