First make sure you cut your wicks at an angle and point them down at the juice channels so that when it fills it goes back into the tank(Screw together the rest of the RBTA). Second is to close the air vent ring. Third is hold your finger over the chimney while filling it with juice and don't let go until you screw in the fill hole. Fourth is to screw it back onto your mod and unscrew your air vent ring. You can now vape in peace since you don't have the RBTA leaking any more!

P.S. DO NOT PUT COTTON IN THE AIR HOLES WHEN WICKING. IT WILL CLOG THE FLOW OF AIR AND RESULT IN LEAKING AFTER ASSEMBLY!

If your Fogger is leaking it is because of too much WICK!

Here are the guides to follow if you are still having trouble. Happy Vaping!

For Proper wicking:
How I wick the Fogger V4 - Imgur

For Proper filling:
fogger no leaks!