Yeah, it's most likely 1) a wicking issue,. If not, then the next likely hypothesis is 2) an O ring issue (check that little one that sits on top of the chimney) or 3) something is not properly tightened. If there isn't a vacuum holding that juice from flooding the chamber, you're going to leak all your juice out in no time.
As others have said, if you fill it from the top, you're going to have a mess.
As far as wicking goes, I have the opposite problem--too much wick.