I've used the Billow V2 for years now and liked it so much I got a spare and measured all the o-rings and got plenty from fastech. It's normal to occasionally get a leak due to wicking but it seemed to be happening more often lately. I changed all the o-rings and not much change.
However I had never removed the center bottom screw. I didn't know that the deck came apart more. Wow, a hidden o-ring. I changed that with a 14mm x 12mm and all is fine now. That size o-ring I think I had bought for my Griffin tank (which by the way is shelved because that was a leaky mess all the time). That o-ring didn't even look damaged, but I guess it gets a lot of heat.
However I had never removed the center bottom screw. I didn't know that the deck came apart more. Wow, a hidden o-ring. I changed that with a 14mm x 12mm and all is fine now. That size o-ring I think I had bought for my Griffin tank (which by the way is shelved because that was a leaky mess all the time). That o-ring didn't even look damaged, but I guess it gets a lot of heat.