Front one not used for about 7 years, did not open today.
Moved a bit the shaft of the gearmotor trough the tiny ceiling access door, and was able to electrically lift the glass, (first stage). Now does not close, sounds like gears jumping teeth.
What is the proper manual action of the gearmotor shaft to make it work ? I suspected it was possible to open and close turning its torx screw shaft, but it is not happening. Afraid of giving it too much torque and break something.
How does it work ?

 

It is possible to strip the gear, sounds like you did it. Take out the motor, disassemble, pull the motor housing off the rotor. You will need to clean it then lube the od of the rotor with heavy grease. Once you put it back together you can turn it with the allen wrench. plug it back in and trigger the switch, it will stop in the correct location. Then bolt it back up.

 

Thanks.
The rear sunroof untouched also for 7 years, does not show action. Some relay clicking type of sound, as the front initially did.
Nothing has been forced at all, no jumping gears noise.
Is the rear one also able to somehow operate manually ? Both did work fine years ago, nothing tampered nor forced since.

The service manual shows the manual crank 'option' as part number M76 3061 . Unable to find such on a search

 

They can be operated manually by inserting an allen wrench in to the center of the gearbox shaft - you remove the trim cover and insert there. However your description indicates your motors are seized from water intrusion, which is a common problem if they are not regularly exercised. The fix is to remove the gearmotor, remove the motor housing, clean the rotor and interior, lube the rotor with heavy grease, and reassemble. It will work fine after that.

 

Well, it is not like that. Have you done it ?

Observing the mechanism, found that cannot be actuated manually unless the motor is removed from the gear assembly, as the motor shaft is a worm and engages its driven red gear that mate the cables moving the glass.
No way to turn a gear coupled to a worm.
Found the gearmotor working perfect when detached. Found the glass mechanism became hard to turn by lack of exercise; I was able to close properly by hand pushing the cables.

So for the next guys who want to manually operate the thinghy, the gearmotor assembly has to be removed first and separate the electric motor from it and reinstall the gear assembly alone. Then the hex shaft can be turned manually. Perhaps will help someone.

By the way, found very convenient to discard the four round-head torx screws holding the glass and replace with hex head 5mmx10mm. Then can be removed/fastened from inside with just a wrench without dismantling the ceiling.

 

Not all worm drive system won't backdrive, depends on the pressure angle of gear. Without getting in to the mechanical engineering design, suffice it to say from experience the LR sunroof motors will backdrive if they move freely.

Glad it worked out for you.

 

OK. thanks ! If can be manually turned then the gear has a built-in clutch.

Found the rear sunroof motor corroded filled with rain as you predicted. And was able to remove the gearmotor with the ceiling in place. There is a screw above its switch that has to be first pryed out to access. Then, the sorround trim rim pulled and allows tight access to the gearmotor mounting screws with a hex wrench and torx bit.
Similar to----> https://www.zoro.com/e-z-red-ratchet...05/i/G6403750/

 

Put a coat of heavy grease on the motor rotor to prevent future issues, and regularly exercise the motors.