[ChillyB]

I'd try detail stripping and cleaning slide. Inspect extractor hook to see if its chipped. Clean extractor plunger channel.

Did the problems start mid-session, or at start of session after you had it apart to clean after last session? Is the little plastic knob installed on back of the extractor spring?

 

[ChillyB]

Good point on mags. I numbered mine to track any malfunctions until everything was established as reliable. Until getting rid of 336 ejector it helped me to eliminate mags because ALL mags performed equally poor.