After replacing the noisy extruder (Morgan0 did a beautiful job here) Morgan01’s prints improved… A lot.
In the photo you see some calibration blocks, a 200mm high, 40mm diameter tube, printed spiral vase style in order to test the smoothness of the complete usable Z-movement, after adjusting the holding tension of the backlash spring. There were some strange artifacts in a large print I left to work overnight, which prompted this action
The Z backlash should be adjusted to the pint where the bed almost wants to drop down on its own when not powered. This allows a silky smooth movement, and is apparent in the consistency of the tube.
The piece of tape on the bowden tube was used for the extruder calibration. Did not take it off yet.