Does it hang down only when it is closed?

If so, it makes sense to me that the guides are not lined up directly across from each other. When they are proper, simultaneously they will contact a "ramp" in the frame of the sunroof when the roof is nearing closure. The roller at the rear edges of each side of the roof roll up this rame and this is where you get the "lift" at the closing that presses the panel up into the hole in the roof of the car.

Typically this imbalance means the cable has slipped a bit on ine side.

Repair/alignment involves taking the thing apart to some degree, using common hand tools. Suggest you find a buddy who has the Bentley's Repair Manual. I can's say if Haynes has the illustrations you need. Bentley does.

On my '84 GL, I had to remove the black flip up wind deflector because it repeatedly caused the lid to deflect of course and misalign to a poor close.