volvospeed shows this for pre 2001 V70 and 850s

http://www.volvospeed.com/Repair/sunroof.php

4th picture down shows the screws.

On 2001+ V70 (This is what I have), do this

- Use your sunroof button to tilt the back of the sunroof up
- Pull the top of the apron (the accordian looking plastic thing) off starting from the back. Becareful not to rip it. The apron detach at the top where it mates with the glass. 3 clips holds it in the front, middle, back along the top. Don't slide the sunroof back when you have the apron off. I don't recall if it will run into anything and rip.
- You will see 2 torx screws along the sides. Tighten the loose one.

I actually had rattles in mine. (during high speed in high wind conditions or high speed with some bumps) After taking the sunroof glass off and doing some inspection. I think the the roof sliding mechanism has a lot of losely fitted plastic moving parts. They vibrate when the sunroof glass put its weight on it. What I did is

- Close the sunroof with top of the apron pulled off
- Losen the 2 screws
- Push the sunroof up and retighten the screws. You might first try the specs here to see if it is good enough for you to get rid of the rattles.

http://www.volvoxc.com/resources/how-to/pdf/sun_roof._adjusting.pdf

This way, the roof glass seals keep the glass up higher and not push down on the plastic mechanism. This got rid of my rattle.

Here is a picture of mine with the aprons off. You can see the clips and one of the screws.

http://img6.imageshack.us/img6/6987/dscf00044mu.jpg
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2001 Volvo V70 T5 ASR Wife says we are Volvo for Life, 1992 BMW 535iA becoming The Ultimate Driving Machine