After tearing apart an atty, I've come to two conclusions. First, these wonderful contraptions seem like a spark plug. When they "load up" they seem to foul. Thus, upside down with a tissue in them can clear them out. Second, being that "juice" has sugar in it and overheating an atty may happen, they tend to carmelize. When mine produce nothing but steamy vapor, I will put them in a shot glass, sprinkle a pinch of baking soda on them, fill the glass with white vinegar and soak for an hour. After this, I boil the attys for five minutes in filtered water and let dry over night. I do buy a fresh atty every month for backup.(I have a lot now) hope this helps.