Hi Chopper,
I have just spent some (many, I'm clumsy LOL) hours trying your Go Go tank method. Got two done and they are working, huray! I had actually given up on the Go Go as the carts don't work well for me, but now I can use them again. Next I'm going to make one for my Volt carts.
I did some things differently though. I mucked around with the syringe plunger rubber thingies and found they were fiddly to get sealed into the syringe. I'm in Australia, maybe those black rubber bits are different here, they are quite flimsy. Anyway. Then I remembered that I have nice rubbery pencil grip doobies, and cut a ring off one of them and viola, fit perfectly on the Go Go cart and into the syringe. I cut another ring for the top seal, no problem at all and seals it tight.
To fill, I used a sharp needle on a syringe. As the pencil grip whatsies are like a soft, silicone, stretchy substance, I'm able to push the sharp syringe nicely down the side of the top ring. There was one problem though, it leaked all straight out of the bottom of the cart. So I put one of those white soft rubber caps, the one with the plug in it, on the bottom of the cart. Had to cut the rubber cap down a fair bit, but then it fit fine. After filling I let it sit for a while, and did get some drips out the bottom, but that stopped after bit.
So far I've only filled to just above the cut I made in the cart, it kept running out and I wasted a lot of precious liquid, sob. That was before I used the plug in the cart, but I haven't been game to try again. Still, there IS liquid above the cut and it's not leaking now, so it looks promising.
Thanks for sharing your great method, I'm anticipating lots of happy vaping on my Go Go at last! I wouldn't mind ordering some from you, but don't know if you'll ship to Australia.
Tgirl