Route the belt through the x_carriage.

Continue to route the belt around the idler of the x_end_idler_tensioner and go back in the direction of the x_carriage.

If you have difficulties to pass the belt around the idler you can tape the belt end with the end of a zip tie. Then, feed the zip tie into the idler.

To finish routing the belt, partially insert the belt into the x_carriage

The belt should have almost no tension, it will be adjusted later.

Trim the belt to length, leaving a few teeth to extend into the center space. Finish by fully inserting the belt into the x_carriage

Verify that the belt is fully inserted into the slot and that it extends into the enlarged center space. You can use tweezers or a small screwdriver to ensure that the belt is pushed fully into the slot.

Verify that no cable is pinched by the belt.