One of the dangers of online research is both the piles of data

combined with "Who do you go with/trust?"
"It's the extractor or springs."
"It's the ejector."
"It's the -"  On and on.
Because there are so many things that may have affected this particular rifle, but might well mean nothing to any other.

Which reminds me of a tale told about a week ago, guy had bought  modular trigger for his AR, and it wouldn't operate correctly.  He brought it to the gunsmith and told him about it, and it was tested.  So they started checking and replacing things, on and on, and nothing worked.  They finally decided "We've changed/tested everything except the lower receiver, let's try that" and stuck it in another receiver of the same brand, using the original bolt carrier group, buffer stuff, etc.  And it worked flawlessly.

And yes, they checked everything on that lower, inside and out, and could find nothing to explain this.  Obviously there's something off, but...