Please excuse my crude photo of the parts, but time is short... The upper extractor (on the left) and pusher (on the right) have had the 'corners' - for lack of a better term - radiused, while the bottom pair have not. A little explanation of my terminology - the 'foot' of these parts is the bottom part that fits into the bolt nose, and are not visible until they're removed from the bolt. The corners I'm talking about are on the backside of the parts, at the point of the transition between the upper portion where the extractor hook or pusher faces are located, and the foot. Visualize how these parts move as they have a cartridge case rim shoved up between them as it's fed out of a magazine - they both pivot outward as the rim puts pressure on their faces. That corner I keep talking about can rub against the bolt bore of the action as this happens - a tiny amount of contact, but contact nonetheless. If this contact occurs, when the cartridge case is pulled back to the point where it contacts the ejector after firing, it makes it basically impossible for the extractor & pusher to spring back a tiny bit to more easily release the empty case and allow it to fly out of the ejection port cleanly.
The plungers are the small rods to the left of the other parts in the photo; they bear on the notch in the foot, with the plunger springs kept concentric to the plunger axis by riding on the smaller diameter spring seat at the rear of each plunger. The face of the top plunger has an angle (should be a radius, but they're so tiny I had a hard time holding them and wound up with more of an angle instead of a radius on this one). The bottom plunger hasn't been modified, and so has a flat face. There's a certain amount of 'break-out' force that has to be applied to the working faces of the extractor & plunger before they'll overcome the spring pressure on the plungers and pivot enough to allow a case rim to either be pushed up between them when it's fed out of the magazine, or to release a fired case when it hits the ejector as the bolt is retracted after firing. Reducing the area of the plunger face by cutting a radius on it reduces the amount of pressure it requires to constitute the 'break-out' and allow the extractor/pusher to pivot and pick up or release the case head. So, not only do these modifications make ejection more reliable, they can also contribute to smoother feeding. Paul sent me a text containing perhaps the same video that DownhillFromHere mentions in his reply above, and working with a Dremel tool and magnifying headset, it was relatively simple to duplicate the mods he described. But as Mike said, with the updated extractor kit, it's a fairly simple process to swap out the original parts for the new ones.