Now I got some time and adjusted the wheel distances of the carrier by loosing the allen screws and turning the eccentric nuts as described here to get a nice fit between the guides. I did this for both Z modules and the X module. I have found the allen screws in the X module to be loose at first. Moreover, I was able to change the distance between the wheels on both sides of the X module carrier without turning the eccentric nuts, just by moving the allen screws. Is this normal? Or is my carrier module damaged?
In the end it took me around 4 hours for everything. Taking another 2.5h to print the initial object again with the same firmware version and same Gcode just to find out that the helix is still present but with a larger pitch now. My next step would be it interchange one of the Z modules with the X module to see if this makes any difference. But probably not before new year…
Any other ideas or insights on this in the meanwhile?