If waxdab23's answer isn't enough - which do you have? They're very different mouthpieces. The CFX one you can soak the whole thing minus the rubber ring that goes around it, the CFV you should only pop off the mouthpiece you put your lips on from the main mouthpiece assembly. You can unscrew the mouthpiece filter and clean it with ISO as well, and use qtips to ISO around that area. You should not use ISO on the CFV mouthpiece assembly outside parts though as it will strip the paint if you have a red unit especially.