how do i know when it time to change the atomizer head ? my ego-c starter kit came with 5 heads, been using this one for 2-3 weeks mildly, today the hits became small and slightly harsher. how od i know if its flooded or needs to be replaced? the wick looks recessed and almost dark in color. want to get as much life out of it as i can before i crack open a new one. thoughts?