For what it's worth, failures to eject are nearly always caused by a poorly fitted extractor. The extractor's real jobs are (1) to hold the case on the breech face where the extractor can strike it, and (2) provide a pivot so that the case rotates to the right when the ejector does strike it. If the case is not on the extractor, either the ejector will miss it or it will push the case forward, where it will strike the barrel hood or chamber and bounce back. The case needs to pivot to the right to get out of the ejection port.
In most cases, the extractor does not actually pull the case out of the chamber. Newton's Third Law does that. You have high pressure in the barrel, squirting the bullet out one end and the case out the other (once the barrel unlocks from the slide). There are guns that are designed to operate without an extractor. Check out the Beretta Tomcat and Bobcat, for example. Those guns have large ejectors, placed somewhat lower than is usual.
When you have a sticky chamber, then the extractor will actually extract the case from the chamber –– or try. If the chamber is too rough, the extractor will slip off the case before the slide has reached the end of its rearward travel. Then the extractor may miss the case or not be able to pivot it to the right, or the case will remain partly in the chamber. The gun will jam in any of these scenarios.