Rince, soak in vodka, rince again, dry out, dry burn the coil, if all that doesn't work after one attempt I get frustrated and CHUCK the #$#% thing... I find with the Kanger Tanks it's hit and miss. Once the coil starts acting up or tank starts leaking (usually because of the coil) I give it one attempt to clean and fix and if that don't do it I just move on and get a new coil and it's back to happy vaping.
I've graduated and found myself using the kanger tanks less and less and have moved on to Hcigar Kayfun 3.1 Plus clones, better vape, better flavor, rebuildable coils are awesome, wick with some cotton. There is a bit of a learning curve to them building the coils correctly and to preferred ohm, getting the cotton wick right, and learning how to top fill it (best method) correctly but once you've got it down it's a new addiction and way better than my protanks.
Also picked up an Hcigar Nemesis Mech Mod and I'm heading towards the dark side... LOL...
Downside to a kayfun 3.1 plus is they tend to go through a good bit more ejuice than the protanks, but I'm finding it's worth it.