I've been using the 18650 and a 510 atomizer(my preference) since I purchased my GGTS. It has been working great until the last few days. I can't pinpoint what is wrong. I do have the leaking issue which I am waiting for Rob to get his supply in but I don't think is the problem. I checked the batteries on the multimeter and they are fine. Took them out and used them on my prodigy with no problem along with the atomizer no problem. I just put in a 14500 with 2 spacers and all is working well. So why won't the 18650 work anymore? Is it the cap on the bottom or the spring? Please help.