It sounds as if you are having a timing problem. There are a set of switches inside the sunroof motor. They stop the sunroof at the right time. You have also a clutch in the sunroof motor. If the sunroof has too much resistance or hits the end of its travel, the clutch will slip so nothing is damaged.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
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