Actually, my buddy had the same gritty pull on his model 10. He followed the same steps you did, and what @william_garcia said about ceramic stones made him grab one for the sear. That little bit of extra control really let him polish the surface just right, and now the action is silky smooth.

Wait, you kept it on the same setting for everything? Tbh that’s just asking for trouble on something as finicky as a diesel pump. No wonder it finally bit you.

Honestly, is it actually creating more work, or is it just annoying to watch? I'd need to see the numbers on those repeat calls before making it a thing. Maybe just ask them to walk you through their process next time, like you're curious, and see what they skip.

Nothing says 'fixed forever' like welding a gate to rebar.