In your slicer check your z-seam overlap. Lines like that are what happens when a slicer is systematically trying to hide a seam while not adding a ton of time onto the print by adding in a bunch of additional time for travel.
If the x-axis rods only move in the x axis then there’s no problem, but if they aren’t firmly secured in the other axes then there could be issues. If they’re able to move then presumably they aren’t secured that well. Given the relatively small forces involved in 3D printing though, you may well be fine.
There are several possible causes for this. From least to worst:
The part itself is good, but the faceing cover plate is misaligned. No action needed.
The part is mounted in a way that makes it wobble, re-mounting helps.
The part is bad and needs to be replaced.
So, let's see the anatomy of a Timing Belt pulley. They exist in basically 3 general types in ...