I'm not suggesting anyone do this, but I had good luck with this. I almost everytime clean the cone with dry Q-tips when refilling the tank (Under the atty base, the well for the battery, and inside the cone). Every few days, I use vodka on the Q-tip to do this (Cleaning the threads w/ one end, drying w/ the other end). When inserting the tank, I insert horizontal and when it connects I rotate it one full turn (In this way you get a secure seal with no leaks). On an older atty (Close to a week, or when I notice poor vaping), I just fill a tank about half way with vodka only (No e-juice; Rinse and dry the tank before inserting the vodka) and vape (Don't inhale). Once done, I remove the cartridge and do a few dry burns without the tank. Rinse the tank and thoroughly dry again (I dab everything cone and all with a dry Q-tip again). Return to normal (Fill tank with e-juice). Works for me.