I have a Kaos Spectrum that was great when I got it. Now it feels more like an effort to pull on in. Usually I can just breathe my mods in, but this one I have to actually pull on it like it's a cigarette. I've cleaned it, I've used different matched sets of batteries. I've increased and decreased the wattage. I've changed the tank. BTW, I'm using a Crown III, but I've been using that since I got it. It just seems as though this mod has lost its will to be vaped.