Tried to assemble and fill a tank last night. Dripped into the carto and then filled the tank. Must be a trick to getting it wet. Let it set overnight and will try again today. It was still dry when I tried it last night.
I use a syringe to prime a carto. The Smok XL cartos hold 1.8ml of juice so I put that much into the syringe. The needle is inserted between the inside of the carto tube and the filler material all the way down to the bottom of the carto. Then I slowly withdraw the needle while releasing the juice, soaking all of the filler material. This is the fastest way I've found to prime a carto.
While priming a slotted or punched carto I cover the holes in the carto with Scotch tape before filling. This prevents leakage during filling. Some people use a carto condom for this purpose but Smok carto condoms don't cover the holes I punch into the cartos.
I drip filled non-punched cartos for a long time. High percentage VG juices will not soak into new carto filler without some help. The thick juice will bead up and sit on top of the filler material without soaking in. Just drip three drops of liquid onto the filler material and give the carto a hard thermometer shake once or twice. That will force the juice into the filler material. Repeat this process for the next nine or so drops. After that the liquid should wick into the filler material on it's own without shaking it down.
Once primed, gently blow excess juice from the center air passage inside the carto using a drip tip on the carto. Then remove the tape (if used) and you are ready to use it in the carto tank.