With this problem you have to get someone to hold 1 section at the join while you turn the other stuck section,tell the person holding not to squeeze to tight or they will crush the section but they must hold it tight enough to stop it turning.As you turn your section pull slightly at the same time try and do this slowly bit by bit,i`ve had sections really stuck but by using this method they will come apart in seconds you shoudn`t need to use lubricant,also wet the section your going to turn and then dry it off as this helps you to get a better grip.Hope this helps.