So, my mom lives a couple hours away and I got a text from her saying that she can not get the mini Protank to unscrew to refil the juice. She's been using this this tank for a while and hasn't had any problems. She just filled it last night. Now, she says it won't unscrew. She said she's tried everything. Without being there, I don't know what to really do. I didn't know if anyone has experienced this (even on other tanks) and if there's a trick to getting it off? Any help would be appreciated.