Not sure how much it will help if the threads are off, but you could try putting it in the freezer for a while and try again when it's ice cold.. That's helped me in the past with stuck metal parts!
Stormy the fact that you can't get the mouthpiece off is not very good news because that means that it's cross threaded. If you have frozen the whole thing (mouthpiece and ceramic housing) I suggest you put the mouthpiece base that is cross threaded over an open flame to heat it well. That way the metal will expand a bit and perhaps come loose. You need to have the two pieces at extreme temperature differences. The Ceramic housing frozen (to contract) and the mouthpiece really hot (to expand).