Recommend you pull it apart and inspect the cables for wear. Also be mindful the roof lining trim on the inside of the sunroof can catch in the slides and prevent the sunroof sliding. Take the 2 screws out of the trim located near the front of the sunroof and slide it back out of the way. You can then undo the 4 guides on the inside of the sunroof lid and lift the sunroof out of the way. Then undo the screws holding the covers over the cable guides. Don't lose the screws as they are expensive to replace. Lift the cables out and inspect the cable, what I found with mine was where the cable located in the winding mechanism was worn flat and wouldn't engage the drive wheel.
I got some replacement cables from the US, the robbing thieves in Australia want $825 for a set
.