I analyzed carefully the rifle and took some pics.
I get the impression that the extractor has “eaten” into the metal where it locks. I’m surprised because I though the metal of the extractor would be softer.
This kina makes sense as I started having the ejection issues since last year (rifle purchased new in 2010).
Can this be the issue? I’m thinking of getting a steel or bonze brush and give the chamber a good scrub.

BTW, I chambered and extracted an unfired round and didn’t notice any blurs on the round.