Sorry can't help to much because mine doesn't leak at all... In fact I have never had a leak with whatever build that I throw at it.
Maybe check what Brian said... I had my center pin loose at the beginning but I've tightened it up at the first time I got it.
My problem is juice spitting back ... It is consistently spitting juice back at me with whatever build I throw at it. Tried the pre-made coil and it also spits back like hell... O that darn hot juice.
It helps if I fire it for 3-5 secs without sucking it... But after 5 puffs, hot juices back in my mouth...
As for dry hit, as long as I remain up to 25 watts at 0.5 build, it won't burn the cotton. After 2 days I will have to re wick... Cotton got blackened on the areas that touch the coil, coil got gunked and flavor became a bit mutter compared to fresh wick
I'm having the same issue of juice spitting back and that juice can be a bit hot. I had the same issue even if I rebuild or use the coils that came with it. But the 25 mm one I have zero issues with. So now my tank sits in my stand and I don't use it. That was a waste of money. I only got the mini one as I like the big one but have to use the cone piece as my shark doesn't like the spring loaded pin it came with. and of course they came out with the one that doesn't have the spring loaded pin for the 510 connection.