Why would Co2 pressure drop to zero over time once set on the regulator? Seems like if there was leak if would continue to have pressure it would just be leaking at the same time. For the first few kegs that I carbonated I did not have this problem. The only difference is that recently I did add check valves since a small amount of beer was coming back through the lines. Is this likely a faulty regulator? I bought the regulator second hand and would not be surprised if it was the issue, I just want to make sure it is before I spend money on a new one.