[voyager4520]

If you have an older Glock that ejected fine for the longest time but only recently started ejecting erratically, I would first try changing ammo, doing a detail strip cleaning particularly around the extractor and the slot in the slide that it fits into, and I would try a new recoil spring assembly. It's possible as well that part of the claw of the extractor chipped off or has worn down and you may simply need a replacement extractor.