Aspire and Kanger Tech are notorious for shipping out bad batch of their coils (including OCC).
You really cannot avoid bad coils now and then.
I honestly suggest purchasing RDAs and build your own coils.
It might seem overwhelming at first, but its actually really fun once you get the hang of it.
I agree 100%
I kicked all of my tanks that use premade coils to the curb just because of spending good money on bad coils.
I was getting coils that had the cotton jammed in there so tight I was getting burned hits at 15-17.5 watts when they were supposed to be good at 30-35 watts.
For a while I used RDAs then got a Goblin mini BC and making my own coils and wicks. Then I got a Kayfun Lite Plus with a bell cap that has flavor almost as good.
I too find making and wicking coils enjoyable.
Neither tank leaks.
Wicking coils takes a knack. You want the cotton tight in the coil but not so tight the cotton. Is unable to slide.