Yep, I'm not exactly sure of the issue he is having, but from what I read into it sounds like an extractor issue. Either the tension on the extractor is not right (which could be the spring issue you mention) or an issue with the extractor itself not having the right specs, etc. Replacing an extractor or the spring is an easy fix on a Glock if that is the issue.
It takes all of about 30 seconds to change it all. I thought about letting glock fix it. But I also knew itd probably cost me $30 in shipping plus a longer wait. I got the part from MidwayUsa and had it fixed in 2 days for just a few dollars.