It's really pretty easy. I just do a drip at time...it sucks right in then I do another drop, repeat a few then roll it a bit to distribute the juice. Repeat 'til full. Not bad at all and a lot easier than the syringe.
Yes, it is easy, and not messy at all unless you get in a hurry and try to pour it rather than drip it!
You start slow, just put a small drop right on the battery hole and it will suck the juice right inside... unless there's a air bubble stopping it from flowing. If at the start (or at any point) the droplet doesn't sink into the hole, just give the carto a few sharp but gentle taps on the table, like you were tamping a cigarette to pack it tighter. I usually tap it about 4 times after every 4 drops. That also helps me count drops. It should hold right about 16 drops without overflowing, depending on the size of the drops and how empty the carto is. Anyway, as you see how fast the drops get soaked in, you develop a rhythm to it and it just seems to soak each drop in as fast as you have the next drop ready. Done in 30 seconds, with no removing parts and no tools needed at all, not even a paper clip!
The one thing about filling this way that is sometimes a small problem is that the air shaft from the atomizer to the mouthpiece has an opening right near the threaded end, so occasionally you might drip some liquid into that passage that leads to the mouthpiece. I don't know of any way to prevent this, but it's the same effect if you over-fill it... juice sometimes works its way to the mouthpiece. Don't worry, it won't kill you! In fact, I get a nice buzz from it! LOL
