I just got a chance to try my 510 this a.m. and I'm loving the taste. One thing I am noticing though is once I hit the button, I'm hearing a crackling noise. I hear it sometimes while I pulling in vapor, too. I think I saw somewhere that it can mean the atomizer is being flooded, so I'm wondering about how many drops I should put in my cartridge when I refill it? It came empty and on the initial fill I used about 15 drops and it was pooling at the top. Took a few drags, went to school, came back, and took a few more drags. It seemed like the vapor was less so I refilled the cartridge, but only 7 drops this time... Do you think I'm overloading the cartridge and/or flooding the atomizer? I didn't think it would be too much of an issue since they say to drop some e-juice on the atomizer anyway...