When I change my tank (just a regular old Evod single coil, but the same head/coil as the PT2), I make sure I grab the battery and the head and loosen the tank first just a TEENY bit while its still attached to the battery (keep it UPSIDE DOWN just in case!!!).. Ive had mine get stuck a few times and found that keeping it on the battery gives you some extra leverage to twist it if the head wont come off on its own.. If Im just doing a quick refill of the same flavor I dont even bother taking the head off the battery. Just unscrew the tank and fill it and put it back on..