the 'locking' bracket that extends to the edge of the roof has a little roller at the end. It is not uncommon for these to break apart with age. First you need to take the sunroof headliner out, it comes out in a snap. On the lever that you twist to lock/unlock the sunroof there is a little clip that you pop out with a little screwdriver or punch. WATCH OUT for the little pin and spring that are above the lever, it is best to put a blanket across your lap so you don't drop it between the seats. Then remove the chrome trim piece. Open the roof and slide the sunroof headliner out to the front. Then close the roof and you will see the entire working mechanism. Inspect and repiar as needed...

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