So in short, is this what you do?
- Prise the hard plastic seal away from the roof enough to put sealent underneath, squirt some under, and then push it down and allow it to cure?
Or does it involve slightly more distruction than that?
I've had great success (at last!) by using the roof and gutter sealant from B & Q. Have only just been able to confirm that it has done the trick as my son lives away from home whilst at uni. As stated in my original post, after sealing the frame to roof using the sealant (christmas '08) I ran cloth tape around the sunroof glass to frame just in case my cure didn't do the job. However my son had removed the tape as it started to lift (very brave move!) and to my relief the roof hasn't leaked at all. Still intend to try the mastic solution during drier weather for a more permanent repair.
Applying the sealant: I used an airline to blow as much water from underneath the sunroof frame before applying the sealant. I lifted the frame very slightly with a plastic spatula to avoid scratching the roof panel. The spatula I used was about an inch wide and quite rigid (for prising switches from car dashboards). There was a lot of play between the frame and roof panel and really didn't require a lot of pressure to lift the frame in order to get the pointed nozzle on the sealant right into the gap. I worked my way round the frame applying the sealant very slowly whilst using the spatula. It's important not to leave any space unsealed so I moved very slowly until sealant oozed out as I went along. To make a nice neat job with minimum mess I carefully masked all the way round the frame before applying the sealant (this took longer than applying the sealant). Once I had finished I smooth the sealant with my finger to remove any excess which been compressed by the frame after removing the spatula and cleaned up with white spirit before removing the masking tape. (If you use silicone sealant it is very difficult to remove from your paintwork and I found it doesn't stick very well to car paint). Hope this helps. Will keep you posted when and how I do the mastic repair during the summer.