I dunno what kinda juice u're using and how frequent u wash it, but I also rinsed with warm water and let it soak for 24hours on vodka. I try to look for highest alcohol content vodka and so far been using 50% ones. After soak just rinse again in warm water and let it air dry before dry burning and refill.
One thing on my tanks is that I rinse quite often like every 1-2refills to avoid the buildup. Trying changing to a new coil or re-wick/coil the whole thing to see how it works. although I seldom vape menthol/mint, I always separate tank used for such juice from others.