Well I worked on it another hour,. I sprayed it out with Winchester spray cleaner & shot it out with compressed air repeatedly & from different positions. I oiled it & worked the action
I ran the bore snake through it, swabbed out the action again the best I could without opening the action, blew it out again with the solvent & compressed air, more oil, more exercise, more air.
Eventually it started to loosen up, or rather stop balking, scraping, galling or whatever.
Since it improved, I'm inclined to say screw the warranty and tear it down for a complete polishing.
However, there is one thing that seems odd. I don't know yet. I need to study the exploded diagrams & maybe check out youtube.
(That odd thing was the nub of the ejector, which floats around a little in its hole in the receiver. I thought it looked like a loose drift pin. It's not. It's the thing I grab with a magnet in the pics below.)