Came accros a video on YouTube of Th3D studio about the difference in v4.2.2 and v4.2.7 boards.
They say some 4.2.2 boards use 4988 stepper drivers which have caused a lot of problems for other printer brands as well, eg skipping steps etc. I personally have not removed the heat sink from one of my chips but if these chips are known for these problems and are indeed installed I expect we are only the top of the iceberg