I detached the quick disconnect from my gas post on my corney keg to open the lid to dry hop my beer. I then tried reattaching the disconnect to the gas post and could not get it to stay attched w/o leaking CO2. I replaced the outer o-ring and poppet and even tried a different gas disconnect but could not get it to stay attached. Any ideas on what I should try next? I don't have a spare post to use at the moment.