My sympathies OP with your issue. Remington extraction issues are a pain. Good news is, if it worked fine before, then something changed to make it not work. Duh, right? Here is where I'm going...
Primary extraction shouldn't change over time
Ejector plungers work if the plunger and spring are not broken and the area is clean.
Chambers/barrels change over time...as others have said, could be build up of material carbon/rust in the chamber, or bore.
Remington extractors; there are a lot of things that can change over time with them. I've found a handful of issues with Rem extractors that can cause similar issues. Broken, worn, loose, damaged extractor retaining groove, and how tight the extractor grips.
Ammo can change.
Check each one of these items and see how they are working. Brownell's has a Rem extractor replacement instruction that is insightful.