Leaking is usually due to the wicking. Here is how i do mine BUT i use 50/50 so it might be best to ask someone that uses whatever percentage of juice you do.
I own 3 x v1 and 1 X V 2 and this is how I do it and i don't have any leaks
I wick like usual, cut my cottons so that its on an angle. The Longer part of the angle to the back, where the deck and screws are. What I do is i DON'T leave trails in the channels as many say, although it works for them but for me it always leaked. I then fold it under, onto the deck itself, but if cut properly, the back of it, where the longer angle is, will just tuck under...you don't want it so long that it then covers your air hole. I just want mine JUST enough to tuck under...IF they then do get in the way of the air hole at all, remembering that it is cut on an angle so the longer part is at the back....I push it back against the deck so the hole is not covered. at the same time, naturally I am tucking it under on the front as well. i always keep mine short enough so it either JUST tucks under, or it almost does, but not quite. That way when I put the juice on, it keeps it in place. Reason for my doing it this way is that too much wicking will leak and too much is not good either. But when I have it folded under, the fold itself sits right on top of the channels, not in them, but on top so the juice just rolls right off of it there and down the channel. It does that so well on its own, I dont need to drown it by running wick into the channel as some claim works for them......it never has for me. Again, we are all different and what works for one, as you know, doesn't work for the next but for me, leaving them OUT OF the channels has always been critical. By cutting them on an angle, I can afford to tuck the longer piece at the back under and against that "wall" so it doesn't sit over the air hole so it can afford a bit more length..and it helps to then stabilize the shorter wick, that when dry, without juice, might not quite stay put under...it sometimes pops out, its that short, but by putting the juice on, then I lightly guide it back under and just push it so it sticks there and the juice rolls right off of it into the juice channel.
When I first did it this way, it didn't look as if there would be enough wick at all but it turns out my size is just perfect. Some seem to cut theirs much longer or fuller, etc so they have to cut it from the top down on an angle, in order to fit the chimney over it-----mine drowned when i did that
So snip on angle, tuck under at back, push against back of wall so its not over the juice hole and then soak with juice and make sure that the front than tucks under...doesn't look like much but you have enough there it will just roll down into your channels.
I have, going, at all times ( i have a lot ).......2 x Goliath V1 clone, 1 X Goliath V1 authentic, 1 x Goliath V2 Authentic......1 x Goblin Mini Authentic, and all of those i do wick exactly the same way and none leak.
I have 3 x Kanger SubTank Minis Authentics, 3 x Lemo 2 Authentic, 2 x Delta ll Authentic but those ones wick differently and i have 1 Ulwell Crown but thats the only one, so far, I dont rebuild on and am using TC coils for my iDP 3Li.
I keep ALL those tanks going all the time which can be a bit much but NONE of them leak and not one of them do I leave threads in the channel.
Hope that helps OR someone with your same percentage of juice can help. Maybe mine works for me this way because it's 50/50? Who knows!
The #1 reason any of my tanks ever leak, is always down to my forgetting to close the air hole at the bottom while filling it up
