I am having the exact same issue with my Tevo Tornado and have tried all of the solutions that you have listed. I was looking at my x axis rollers, they are showing some intermittent wear. At one point on the gantry the hot end would be tight, then move the rollers half a turn to the left or the right and the whole hot end assembly would click-click with about half a millimeter play. I made an adjustment to the bolt seemed to tighten up the play. I am working on a test print now. It's not looking to have solved the problem as of right now, (only the first layer down, almost no dragging noises on layer two, and looking better than the first layer) so I am not giving up hope. My next step would be to replace the old rollers with new ones and see if that solves the problem. At least this gives you another course of action to take. Good Luck!