There are supposed to be o-rings in those grooves. One of the tips I read was to lube the grooves through the triangle cutouts and push the o-rings as flush as you can get it into the grooves, then carefully wiggle and twist the tank insert in. Here's the post, with a video link: http://www.e-cigarette-forum.com/forum/general-vaping-discussion/507143-focalecig-new-fasttech-1175.html#post14368031
Yup really easy fix..
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