Hi All, I have been using Vaporesso aurora kit (MTL)for a month now. Please let me know if anyone of you is still using the device. When to replace coil ? Is their a way to clean the coils? - (Coils used is CCELL Mini Replacement Coil) Cotton has not turned black from outside(Getting strange metalic taste) , i am not able to see how coil has changed inside as it is sealed . also please suggest a vape were we have low maintenance cost.