Some finetuning to Z-axis rails and getting quite good results:
https://dl.dropboxusercontent.com/u/...2020.00.58.jpg
https://dl.dropboxusercontent.com/u/...2020.01.09.jpg
https://dl.dropboxusercontent.com/u/...2020.01.21.jpg
https://dl.dropboxusercontent.com/u/...2020.01.36.jpg

Slight deformation, but I can live with it for now.