Well, the return line is basicly the same principle, just slightly different.
A little blue plastic thingy, that is latching on to the black plastic part.
On the right pic it's easy, just put some pressure on what you can see.
The one at the bottom side is a pit of a handfull
In my case i could force it in by putting a thin piece of metal between the blue and black part; exactly at the point of the red arrow on the left pixie.
Now that i have done both, i can say that if you press EXACTLY on the correct places, both connectors should come off with a brease.
I have no idea if the little blue ring should have been attached to the plastic construction or not.
If it does, i can understand that squeezing it could bring the little plastic latches in, releasing the black connectors.
If your blue ring is loose like mine was, just follow above guide.
Edited by smiley, 19 April 2014 - 05:05 PM.