I have been getting these lines where there seems to be not enough filament extruded accompanied by some clocking noises (not really grinding). Recently I got a few errors about stuck filament as well.
I did a few cold pulls but there wasn’t any debris to be seen and the three ends (cht) were clearly visible.
Noises, pattern and errors persist.
Pla, core one, max layer with 0.4 nozzle.
Any help appreciated
Edit is the image not loading for everyone?
A low friction filament path solves a lot of under extrusion issues. See if you can build a filament holder with ball bearings and/or a filament guide before the extruder. It solved all my issues with my former Ender 3.