JCraig, It seems that this problem has not been solved yet, and there is information that needs to be answered.
1. The spring insert (blue smurf) is to keep the spring from colasping, it's mil-spec. The D-fender is added around the spring to add tension to the spring. It's a great band-aid, but masks the real problem, which may be engagement.
Your problem is from two areas. The first is that the chamber is a little rough and once it becomes dirty, the walls start to grab the cases. The fact that the case is still ejected from the chamber is due to the extractor starting the case out, and then is stripped off the rim, and the gases (barrel pressure) finishing the ejection of the case out of the chamber. The bolt is bouncing the case out the ejection port on it's way forward. Time to clean/polish the chamber.
The second area that you are having problems with is the extractor. Start off by cleaning burs from the extractor lip and channel, then move on to the bolt channel and check for burs. The reason that you want to check the bolt is that the extractor must be able to move freely in the channel to allow it to work. If the extractor is tight in the channel (no side movement or pin binding), the slightest fouling is going to bind it.
Also, have you check the extractor for engagement. The extractor/bolt channel rest pad may have been milled oversize and not allowing the extractor to fully grab the rim of the cartrige. Again, check for burs on both, and if needed, straight file the extractor at the bolt pad contact area to allow the extractor to move inward to fully engage the rim, and the bearing sides if the extractor is binding on the channel walls.
Note: The use of a D-fender will apply more pressure to the extractor, and band-aid the extractor by making the extractor grab stronger with more pressure on the limited engagement, but will not last long, due to the extractor only grabbing the rim with a small portion of the lip and cause faster lip edge wear. Instead of a D-fender, a stronger spring can be installed, but if the spring is too strong, the rim of the case will be dented by the extractor lip not gliding over the rim, but by bending the rim to allow the extractor to pass by/threw.
Granted that you could just replace the extractor/bolt. But by cleaning up any imperfections and fitting them, you will not need to replace them, nor wait the 5 days for the parts to arrive.
P.S. One of these days I need to do a Royce and compile a web page on the complete build and fitting of parts. Granted that the repair manual is great for an overview, but due to the different receivers and part manufactures, building an AR-15 is a little more complicated than just dropping in parts. Some times the parts need to be fitted to make then function correctly. This is unless you have bins of the parts that can be tried, and tried, and tried, until the piece/parts are in spec.
Hope this novel helps.