Pull the bolt, and check the ejector to confirm that it is not binding in the bolt face when depressed. If you find that the ejector (#5) is sticking, then you will need to pull it. To so this, you will use a 1/16" punch, and while using a towel to catch the ejector/spring (#5,6), punch the roll pin (#4) that is retaining it. When you go to reinstall the ejector, align the flat of it correctly, then use a spent case on the extractor to retain the ejector in place when you reinstall the roll pin.
Note: every once in a while, the ejector is installed incorrectly (it's flat out of position), and this will cause it to bind instead of the basic problems like burs or brass flakes in the ejector channel.
Also, with the rifle unloaded, pull back on the charging hand and confirm that the front face of the bolt stops/limits out in from of the back of ejection port about 1/4". If the bolt retracts past the back of the ejection port, this can cause the round to be deflected on the back of port and bounce forward back into the system.