Gas connector leak

Finally tracked down the source of why I've been losing 3/4 lb. CO2 every day. Or, at least I think I have.

The gas connector appears to be the culprit. When I hook it up there is a distinct humming and I can feel a slight vibration of the gas line. Short of replacing the connector is there anything that I could be missing to resolve this? Thanks in advance.

I have a 20lb co2 tank split to two distributors and they both hum when they are providing gas. If I hook up a new corny, it will hum for a while. If a keg is fully carbed and I hook it up, I don't get the humming.

I could be totally wrong, but I don't think this is the issue.

I had quite a few hastily emptied 20lb co2 tanks, but have had the same fill for maybe the last 10 kegs (and hopefully quite a few after this). My issue were the kegs themselves...I eventually narrowed it down to 2 kegs. With those two out of the rotation, I haven't had any issues. One of the lids isn't seating correctly and the other's post was leaking - poppet hole looked slightly gouged and top of the post was slightly bent.

I think there are so many more things that can go wrong on the kegs than the tubing/regulator/co2 tank - as long as you clamp well and follow directions. Keep in mind that we are using old kegs that have been used TONS of times...a lot of the parts have gone through extensive wear and tear and need to be either repaired or replaced.