I'm sorry, I keep reading what I type and thinking it isnt clear. Either I am tired or there is a CO2 leak in my house right now. Start here:
clean them/dry burn them to get the primer out, fill your syringe and tap the syringe with your finger to get the air bubbles in the syringe out. Then push the plunger until you hear the air come out (have a napkin ready) Check to make sure there is no air in the syringe. Take your syringe and make sure you carefully poke through the silicone with the CE3 upside down, fill it sloooooooowly and what I would suggest is put 1.2ml only in the syringe so you dont over-fill it. Take the needle out while it is still upside down, swirl it about a bit while upside down and then set it bat side down for a few minutes. If you are 100% sure you have this part right....
Mine leak when they get 1/2 way or 2/3's down. when this happened:
I found that refilling them stopped them from leaking right away. So when I heard the gurgle, I cleaned out the bat, the mouth peice and followed Mr. Outlaw's video for refilling. I also found that taking the tip of my clearo (when empty) and pushing in the center post with the silicone in the CE3 helped......When it gets to that point, keeping the CE3 horizontal so that the juice isnt all at the bottom helped too and I took ones that leaked all the way down by keeping it horizontal (keeping it horizontal while vaping only I mean). Some worked fine on a second or third fill
I also read that putting the silicone back in the CE3 wet would help with the seal and I was told not to mess with it too much. What I did with a leaking one is clean it and set it on the mouth peice side for 15 minutes (I only cleaned it out, nothing else) and no juice leaked on my napkin. I put it the other way and still no leak so I deduced that the ones that leaked, only leaked when I actually used them so I could still carry them around.
I personally think this is a QC issue and I too, hope the new ones work. I LOVE the concept and when these work, they are awesome. I have been trying to systematically break down each step and each peice to figure out why it is leaking and the only thing that I have found is a poor seated center post, meaning that the leaking CE3 that I took apart.......the center post came out REALLY easy and according to others here, easier than it should have been....>BUT, these are fragile and if you arent careful with your messing about, you may break something that works. There were a few that I just re-did the process from the beginning and they are now working.
Keep trying things and if you come up with something, let me know because I am out of options