My 901 makes a noie too. To me it sounds like air moving past droplets of liquid as it goes
through the little hole on the side of the atomizer. It resembles a gurgling sound. When the gurgle gets too wet, I find a flooded atomizer. When their is no gurgle, I find a dry, dented spot on the cotton inside my cartridge. For mine, a slight gurgle is delicious
, a dry whistle is a pointless puff
, and a very wet gurgle is a mouthful of nic
juice. If you pay attention, you will get a feel for it.