I agree...use a 1.2mm or 1/16" hole and keep the hole at least 7-8mm above threads. At 6mm..you may actually be slightly below the o-ring..which could definitely cause the leak.
As far as using the 901 atomizer..i've finally figured that out too. I use a regular SLB 901 atty on 3.7v. I close the CR, fill with juice..seal the top rings. Open CR full open..and vape till it stops gurgling...(about 5mins). It's just a bit flooded at first..but not enough to shut down the atty...so just vape it off. Then when it starts to taste a bit metallic or you stop getting any vapor..close CR completely and then back it off just barely...then draw on the tip without firing atty. You should hear a muffled gurgle. Now open the CR about 1/4-1/2 and you should get a nice full vapor exactly like you'd get with 3-4 fresh drops when dripping. From then on..just wait for the vapor to drop..and then repeat..vaping all day..no sweat! Hope that will help you with the 901's..I'm actually preferring them now vs the cartomizers...but I intend to try the cartos at 6v when my gear gets here.
I've blown two of my most recent modded cartos at 6v today, and this may be the reason why....may have strayed too far from emonty's instructions.
1. Put the hole down lower on carto in an attempt to squeeze every last little bit of juice out of the afs tank.
2. May not have stuffed polyfill down far enough under the drilled hole.
Each time, they vaped fine initially, then tasted harsh/burnt and quit vaping. I'd think this would indicate a carto not feeding problem, but I could taste my cigar juice peeking out from under the 555 juice preloaded in the cartos.
Not really a big deal, it's just that I was wanting to take my ggts/afs with me on my 18 hour drive to and from the land of lincoln this weekend. Not having a vape I can utterly depend on is not an option.
It's not like I can field strip a carto from the AFS while barreling down the interstate at 75 mph. Juice would go everywhere, the kids would be screaming, I'd be cursing....not good.
