To find the plastic clips/pins open the roof 3/4 way and pull down the interior fabric from the front edge of the roof. They are white in color or at least mine are. About four or so of them. Reach in with screw driver and twist it to pop out the pins.
I almost certain you will find the cast metal sliders broken . One on each side of the roof.
1993 190E 2.3
2000 Toyota 4x4 Tundra