I just redid the seal today... My snorkel was fitted by ARB and i noticed the other day that the seal had pulled away..
I had great trouble, I completely removed the airbox then put a thick bead of silicone around the joint the refitted the airbox, before I bolted it back in i pulled it away from the joint to try and get more silicone in there, I then bolted it in and from inside the airbox tried to push as much silicone into the joint with my fingers as i could.
Its drying overnight, I'll test it tommorow to see if i have a good seal