Only a guess I think the clips are in the bottom section and the top is secured by screws accessed through the grill. Can't find my book to look may have left it in the caravan I've just sold.
Bob
May 2011
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix caravans/motorhomes.