Backlash problem after adjusting "Step Length" (um)

I had the problem that my squares where not square. (the X-axes was longer)
So in rdworks adjusted the “Step Length”, now my squares are square again.
But now I have problem (especially with circles) with backlash.
Start and end point do not line.

Do I need to tighten the x-axes tension?

What is the controller used for an HL-1060 blue white? (also add that info to the Machines field on your profile).

Hello Stroonzo,
its a Ruida-6445G
with RDC-V15.01.10 firmware,

Added it to my profile.

Removed the belt and cleaned it.
also cleaned the pulley and guide wheel (those were quite dirty)
put the belt back and give it some extra tension.
in rdworks adjusted the “Step Length” ([08] RuiDa Controller - Calibration of X and Y Axis for CNC Co2 Laser - RD Works - YouTube)

Now its working fine again :grinning_face_with_smiling_eyes: