While playing around with profiles I found on the internet, the scars vanished. Cool, but why? Simple, the layer change does not happen on a single place anymore. Means: The layer x stops eg. at 0° of the outer circle in that tube (I print inside-out to get a better surface, but that makes no real difference here). Layer x+1 starts at 15° of the inner circle. So, you have a really tiny bump at the outer layer and another one, in a distance, at the inner layer. So, you get two vertical lines, only one on each surface, that are almost invisible instead of one big ugly one.
In the end, it was the "Wipe Nozzle" parameter. In that configuration, it wipes the nozzle for about 4mm. It does not matter if you define the layer start next to a specific location or just for fastest speed. Which is a flaw in my view, because when the nozzle is at a specific location after the whipe, the fastest way would be to change to the next layer right there and not go back x mm to start there, but I am happy with that
Oh, and you should switch off "Force retraction between layers".
