Snagged an L.S. Starrett 923 recently, and disassembled and cleaned it up today. I'm so impressed with how well-made these vises are. I was fortunate to get it, since these are super-rare to find here in Canada - in fact this is the first one I've ever seen for sale locally.
The as-found condition was a bit rusty and dusty.
But it cleaned up nicely with minimal effort. The original "car trunk liner" paint was in pretty decent shape, so just scrubbed it with soap and water and polished the unpainted areas using some non-woven abrasive buffing wheels.
The jaws were in almost immaculate condition. The only dirt I found inside the vise when cleaning was some sawdust, so it was probably not used for much other than holding pieces of wood steady while sawing.
I was quite surprised to find out that the screw was threaded with a "buttress" thread rather than the normal acme thread. I've only ever seen buttress threads on my quick-release style Made-in-England vises where it works nicely to engage tightly in the half-nut when tightening but slides easily across the nut when using the quick release feature. Wonder why Starrett used this thread type?

Thanks for looking,
Tom