Hiya, i had the same problem with my 03 scenic, the drain tubes are located in the front corners of the roof nearest the windscreen, i cleaned mine out but found little or no dirt in there, the roof with continual use has seals on the mechanism all round and they fail, you will need a dry day, a tube of clear silicon, a small pair of step ladders and a wrag, you have to look and determine where you think the water ingress is, i noticed at the front of the sliding mechanism rails were small holes, i plugged them with silicon and then looked for anything else i thought looked like a potential leek, i had to physically stand in the car at one point with my head poking out just to check i had got everything, it really is trial and error but if you keep at it eventualy you will cure it, let it dry for as long as you can with the roof open, see how you go in the rain if it still leaks then you need to repeat the process, it took me two good afternoons to stop mine leaking, but finally it worked and the interior windscreen trim finally dried out. hope this is of some help.
WAKEY GEORGE., February 2012
