I got the Lemo Drop 2 weeks ago and just as the OP says, worked great for the first 2-3 changes of cotton, and now leaks about 1 ml or less. It's just at the centre pin on the inside. No leaks from the silicon plug. I've checked all the o-rings, white and black and they're all intact. I do fill right up to the brim of the tank, using a small 10 ml hangsen bottle that has a nozzle small enough to fill the tank. It does force the liquid into the tank. Could that be causing a pressure build up in the tank and thus causing a leak? Earlier I used a syringe for the refilling and did not have this leak issue. Was hoping to figure out if the OP ( Baums) has sorted out the leak problem and if there is a fix for this. Thanks!