Don't do anything rash until he puts a M-4 extractor spring and insert in it.
Sounds like the extractor is letting go before the ejector can punch it out.
Failing that I would try a new ejector spring.
Get one of these while you are at it as they are cheap. May not need it but it is cheap.
I would advise him to dump the 10 1/2 inch upper and get an M-4 upper. Thats how I fixed a pre-ban with I bought(Actually, it was a 16 inch pencil barrel and not a true M-4 cut barrel.).
Try the stronger extractor, it is the cheapest fix and if as described is his only problem, it will proabally work fine.