Need definitive W210 sunroof repair info

[ProV1]

I've searched & searched, and there are conflicting info regarding DIY repair on W210 sunroof not opening fully.

I've read:

1. Remove the glass, lube & clean the cables and everything works

2. Remove the glass, bolt down the cover plate with an extra screw

3. Remove the glass, and replace sunroof cables and cover plate


So what is exactly the right method, and exactly what parts (MB part #?) do I need for the job? mine opens about 2" or so and then the motor spins freely and nothing grabs. Thankfully it will close though.