I have been having some problems with my Griffin feeding juice to the juice channels. A vacuum seems to build in the tank I can see the air bubble in the juice hole. If I crack the top of the tank as if I were going to fill it, the bubbles come out but that is the only way. And I mean a lot of bubbles come out like the juice well was completely dry. I have tried different wicking techniques and different coil diameters but the problem seems to persist. Any ideas on how to fix this?