Or pull the old trigger and clean it with brake cleaner ! After cleaning douse it with lighter fluid and reassemble. Make sure he’s not using so much oil on the bolt it runs down into the trigger. Yes the old style trigger was prone to failure but it took dirt and dried oil to get it there. I’m all for a new trigger but even the much better triggers are susceptible to failures from poor maintenance.
If I were going to pull the old trigger for an extensive cleaning like that I'd just go ahead and replace it. It's more than just a safety issue it will give him a far better trigger as well. Simple as dirt to do as well.
