Put my last unused echo single coil carto in to use today. Inspected the coil from the top by placing it on top of the small led light on the back of my smart phone (best way i found). Coil looked perfect, but was not sure if the wire part from the coil leading to the connection were touching the inner tube or not, so i opened up the bottom of carto by: 1) removing the metal center post (While holding in the silicon piece) and then 2) removing the silicon piece. One of the wires was very close to the center tube, if not touching it so i tried to movie it a little with a tooth pick. Maybe it moved maybe it didn't but I was pretty confident was not actually touching the center tube wall. I reassembled being sure to slide the silicone in with one wire on the outside of it, and then slide the center post in with the second wire next to it.
I filled and waited and then the tested it out. 1st puff, great. 2nd, little harsh, 3rd, bad taste. So i opened the bottom back up to recheck everything. Nothing touching the walls of the center tube and coil still far away from the center tube wall on all sides. And there was no sign of charring anywhere. So I decided to push the coil up with a toothpick just in case that was the problem. It moved a tiny bit, but I was being cautious not to push too hard and dislodge the wick.
Reassembled just like i did the first time, tried it out and: 1st puff, great. 2nd great, 3rd, great.....puff 25, great!
Seems like the coil being too low and close to battery connection may be one of or the main issue in these cartos. If it is then the fix becomes that much more simple because it can be done without a full dissemble and would be quick and easy. I think i have been fixing the height issue just as a byproduct of centering my coil better on the ones i have fully taken apart.
Dual
coils are a whole different animal for me, right now im just confused when looking at one after taking it apart. lol