We recently had an issue like this at Mechanical Tempest. At a fortnightly meeting, it came up that one of our volunteers was behaving in a way that was dismissive to people trying to learn, and generally acting like a know-it-all man (very common problem). We decided that the best way to approach this was 1 - amend our safe space policy so we had something to point to if it happens again in the future, and 2 - reach out to the volunteer and tell him the issue that others were having with his behavior. The mechanic that runs a shift with him put their hand up for this conversation. He took the feedback well.
That's a pretty lightweight response in a high-trust group. If he did not take the feedback on, or did not amend his behavior, it would be nice to have a conflict resolution scheme already in place, but we haven't gotten there yet. But at least having an agreed upon policy to point to if the situation escalates is a good start.
Jesse