I purchased a squape clone and while it works great, when I unpend it to refill or mess with the coil/wick, it leaks like crazy out of the top. Is there supposed to be an O-ring or something where the chimney screws into the tank (I'm guessing that the culprit) or am I just not tightening it down enough? I didn't see an O-ring and I don't have one that fits with the spares that were provided. Has anyone else experienced this?