Ask me again in some days to weeks, depending on how much time I have to work on that printer 
At the moment, I am in the process of fine-tuning my print settings (bye Snapmaker controller and Android display, bye postprocessing and uploading skripts - welcome back Duet controller and PanelDue, welcome configurability, expandability and decent web interface - I sorely missed you 
). But the average temp tower does not have that much chances to present a lot of z binding artefacts.
But judging from my previous experience with such a z axis design and from the difference in the location of the hex nuts, I do expect an improvement. Let’s see how it turns out…
@RalosZk now that I do not have to test hotends, I can spend the time with disassembling my J1. 
I plan to remove the z bearings, properly grease them and align the z rods.
The disassembly guide you’ve posted doesn’t include the final steps to remove the bearings. How did you proceed after step 8? Removed the 4 screws on top of the bearing to release it from the printbed? Then lift up the top frame enough to pull out the rod with the bearing?
Are there balls in the bearing that might fall out when I remove it from the rod?
Btw. the anti backlash nut on my z leadscrew is very stiff. Was it the same on yours?
It’s been a while since the last post in this thread, but I’d nevertheless like to thank all of you for your help with soooo many issues.
I bought a J1 with upgradekit in March and had to deal with a damaged / bent z leadscrew, an old version of the x linear rail with play, random layershifts, weird clacking and beating sounds, damaged/loud fan bearings etc.
Thanks to you I directly ordered the new released hardened steel hotends and at least had no issues with clogging.
I didn’t use my J1 on a regular basis because the print quality just wasn’t good at all and I simply accepted the “fact” that my Snappy couldn’t do any better.
Now a friend bought a J1s and showed me his first prints. Guess what, they look awesome! 
I should just set my J1 on fire and buy a new one, mine is a joke. Will it ever just do what it’s supposed to? We’ll see 
According to your discussion I now know that I’m having Z-binding issues which I will hopefully be able to get rid of this evening. I’ll try everything you mentioned.
Thanks again for your help guys!
2 Likes
Better late than never: The smooth rods where not alligned correctly which caused the issues.
Problem solved, finally!!
*Layer height was 0,24mm btw, so not very detailed but enough for testing.
