It's not common but we have had reports of the rear right Z belt coming loose from where it mounts during shipping- You will need a couple new cable ties and needle nose pliers to do this easily. It's easiest to remove the ride side panel to access this belt mount. 

The yellow arrow is pointing at the slot that the belt loops around and the red arrow is pointing at the obvious bend in the belt showing where was positioned. If you want to loosen the belt a little so it is easier to tighten, you can do this as well. See below. If you have any questions about this let us know. 

To loosen the belt so you can snug it back up after attaching, you can loosen the screws at the top 1.5-2 turns each. Then after you pull the belt snug underneath and zip tie, you can re-tighten them the 1.5-2 turns. 

Below, you can see the belt correctly attached. The belt loops around a slot in the metal bracket and cable ties clamp the teeth together.