Unscrew the sun visor after prying off the screw cover with a small screwdriver, unscrew the grab handle after removing the screw cover plates, again with a small screwdriver, unscrew the sun visor retaining clip, then pull down the door seal about a foot from the corner each way.
Gently pull down the head lining and you will see the corner of the sunroof with it's spigot. This should have a piece of tubing about 10mm in diameter on it. If it doesn't there's your problem. Mine was about 1" away from the spigot - I just pulled it up a bit and pushed it back on.