I have a moonroof in my 940. It has persistently leaked and dripped water onto the headliner and on the right front passenger seat. All sunroofs and moonroofs leak water and the tray under them is designed to carry the water out to the four corner drains. I thought the tray or drain hoses were leaking, but that was not the case. The water was leaking between the glass and the rubber surrounding it in the sliding assembly. I carefully masked the glass and the rubber, then applied a thin layer of black silicone caulking. No more leak, but I did have to replace the headliner.
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john