OK, what just happened? I got my new fluxos (well, my first fluxos but the new version) and it was vaping great but a little tight on the draw. So I pulled the plug out to reseat it and see if that made a difference and the whole center stem came up. Or at least the ceramic cup, I guess I can't say for sure that the stem moved. I was able to put it back together and it is still working. It did get a little gurgly when it wasn't before at all, but that seems to have worked itself out. I just want to know what to expect the next time I have to take one of these apart.
I had the very same thing happen. My suggestion would be do not try and pull that center plug out by the little nipple. Instead use a bent paperclip and pull it up through the fill holes, pull up a little at a time from each side.
In order to prevent any juice from getting down the center tube you'll need to heat up the black shrink wrap below the ceramic cup. Remove the tube and moved the wires away from the center post. You can then use a lighter and heat the shrink wrap so it shrinks tightly around the center post. It doesn't take much heat, maybe a second or two but no more. You want to make sure to not heat the wiring. Once cooled pull on the ceramic cup gently to see if it still moves.