I have an Ender 3, I changed its extruder for one metallic one.
In my last prints, I am getting issues at the same height. The extruder can't pull the filament in for that z position.
I cleaned the Z axis, applied oil, and adjusted the eccentric nuts. I have minor improvements but still have many issues with my prints.
I am thinking of changing to double z-axis, but I'd like to use my printer now.

[![enter image description here][1]][1]
[![enter image description here][2]][2]

This is my printer.
[![enter image description here][3]][3]
[![enter image description here][4]][4]


  [1]: https://i.sstatic.net/jUwWG.jpg
  [2]: https://i.sstatic.net/Xpk3T.jpg
  [3]: https://i.sstatic.net/h3l9N.jpg
  [4]: https://i.sstatic.net/tBv9x.jpg