OK, so my silca pump has a rather bulky head that I thread on to the tube stem, then attach the hose from the pump and get to pumping.

The problem is that the connection leaks air (the QD connection), so the pressure doesn't hold and I'm never exactly sure what pressure I'm getting in the tire. It's not a huge problem, obviously, but it's a small annoyance. Is there some way to keep the connection from leaking? It has leaked since day 1. I thought I'd check before putting a little grease on the o-ring in the head.

I think it's an air disconnect issue more than a silca specific issue - this is what it looks like: