I have had my Kanger Subtank mini forever and its been a great tank. Up till today I have only used the .5 watt OCC coils. Today i built out the RBA head on it and at first it hit like a champ but now the hits are pretty hot even at low wattage (15w-17w) I am not chain vaping and Im using the same juice i used with the OCC coils, any ideas??? Not enough cotton???