Hi @vizer40
Are you referencing this post you made before when you said, “I still haven’t solved…”?
You’ve mentioned cleaning and reassembling the machine, but there’s no mention of checking belt tension, pulley set screws, belt–pulley tooth engagement, or general mechanical preload. Issues in any of those areas can cause exactly this kind of artefact, even if the machine feels “mostly OK” by hand.
You also mention the linear guides / wheels (which you referred to as “MGC”), but there’s no feedback yet on the belts or the stability of the diode head itself.
With the machine powered off, try moving the head slowly by hand along both X and Y and note any tight spots, slack, or uneven resistance. Also check that the belts are evenly tensioned and that the motor pulleys are secure on the shafts.