Hmm....the above has cured extraction problems for me AFTER firing, but I've never had any problems getting the round chambered. If it's difficult to load a shell by hand without using the bolt, the above may/should/could cure it. That would mean the problem lies in the rough chamber and not a rough mechanism elsewhere. If not, you're catching somewhere else (obviously...) and need to diagnose the problem and polish/lubricate to fix it.
It's a 5 minute project so it's worth a try anyways...