With the EGO DCT Tanks, I had a hard time replicating the method I normally use when filling tanks. With regular threading I would just tug at the screwy part of the cart until it slid out a bit, but the EGO DCT Tank's ego threading makes this impossible without super strong finger nails or other tools.
I had a hard time figuring out the best way to fill these, but I finally did, and so I wanted to share the method.
1) screw the system into the ego battery all the way
2) remove the tip
3) hold the tank and twist to the left while pulling up. (The tank will slide up the cart)
4) keep sliding the tank up until the carto's top is inside the tank.
5) carefully push on the side of the tank near the top until the cart is angled as such that there is a little opening at the top.
6) slowly drip juice along the edges of the tank's rubber top, making sure to just drip it into the tank and not into the cart.
7) after it's filled 75% of the way, angle the tank with the cart and push down on the tank (towards the battery) until the cart snaps back through the top.
8) If this is the first fill, drip into the top of the cart enough to prime it with juice so you don't burn it out.
9) again, if this is the first fill, let the cart sit for ~5 minutes to absorb the juice.
That is a good no-mess way of filling this system without using needles or even removing it from the battery.