I've been vaping for a few months, and my first pen was a Aspire PockeX, much like the one I have now. My main issue is, the one I'm using now doesn't seem as strong? I've tried replacing the filter, fully charging it, leaving it for a while then coming back to it. Nothing seems to work. The juice I use is 1.8 50/50, does anyone know if this is a known issue?