I have indeed noticed that with the previous iteration. Then I tried to have the idlers on the same screws that would connect the joints to the rails in an attempt to make the build as efficient as possible.

The belts did not make 90 degree paths from the stepper motor towers and also not from the YX joints to the toolhead. This caused uneven tension that was most noticable when the toolhead got close to the YX joint or when the YX joint got close to the stepper tower. The belt angle would change based on the location of either object and that changed the amount of force needed to pull it.

I’ve learned that the belts ideally make 90 degree angles when pulling something. One belt path comes out the left side of the idler and the other comes out of the right side. At the toolhead you insert the belt from either the left side or the right side to make the belt as straight as possible.