I took my two pvc tubing gas lines off of the regulator. I've never cleaned them nor taken my co2 system apart, so I figured why not.. I've had some infected beer, and I figured it wouldn't hurt. Anyway.. I took the two lines off and I'm looking at the ends where the Gas Disconnects go and one I can see down perfectly, and the other is pitch black... What am I missing? Does one have a check valve? Is there a cute little mouse living in there? I'm avoiding taking them apart... but it may be my next step. Ideas?