Two layer shifts. Any idea why and how to fix?

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Change orientation of print, rather than printing vertically try printing horizontally (if visible layer lines are not much problematic). These layer shifts are relatively less in core-xy setup but that upgrade is a big headache and requires lot of skills. Try lowering travel speed and print speed a bit. Also check if your lead screw is properly placed, clean and slightly lubricated. Hope it solves your problem.