I'm trying to troubleshoot a problem/problems for a couple of days now regarding printing issues caused probably by the Z-axis. I'm new to 3D printing and kind of at a loss about what to do next or how to do it right. I hope you guys have some ideas about what could cause it and what to try. (There is also a pic included where you can see missing spots/holes in the print and I also would like to know how to fix that)

- Printer: Neptune 3
- Material: PLA
- Slicer: Cura

What I already tried:
- Readjusting the lead screw and couplers
- Readjusting the belt tension
- Readjusting the rollers

[![Photo of a printed model with printing errors][1]][1]


  [1]: https://i.sstatic.net/K7ouO.jpg "Photo of a printed model with printing errors"