Firstly see if you are using the newer BVC coils or the olders BDC coils, the BVC's are much more reliable. Secondly the nautilus does not like being overtightened. Take it all apart, and make sure the coil is in just tight enough to make good contact, and the glass isn't overtightened either. If that doesn't work then it is time to try a new coil (if you haven't already), or I have heard of people ordering the stainless steel sleeve replacement which I have heard makes it more leak-proof. I only have problems with mine though if it gets too cold, or too low it will start to gurgle.