Check your ejector plunger. When pushed down, does it pop back up? If not, the channel or spring may need cleaning. If you remove the plunger, also check the ejector for burrs. The spring may also be worn.
If the case is not leaving the chamber, then it's an extraction problem. Clean beneath the extractor hook. Check the tension (does it spring back?). You may have to replace the extractor and the extractor spring. It may not even be the extractor and its spring. Make sure your chamber is clean and shiny. Dirty chambers cause the shell to stick. Check your ammunition too.
Vigilantibus et non dormientibus jura subveniunt. Molon Labe!