Tip: Maybe a bargain in finding a machine / thread injector

[Redoleary]

If I could find locally finer grits than the 600 and then the polishing paper another sewist furnished me, I'd have gone that route. Where there's a scratch, there also displaced metal above the surface. Polishing compound won't pare that off. Suggestions of how best to do it are welcome.

You might look for fingernail files/buffers they come in varying grits from coarse to extremely fine.

[DemostiX]

You might look for fingernail files/buffers they come in varying grits from coarse to extremely fine.

Excellent. Of course [slaps forehead], and they're in every drug store!!

And maybe better for the first, very controlled strokes: The small file I've never used that's included with most nail clips

(What would the world of fishing have been for the last 70 years without those nail clips to trim line?)