Hi Lauramumof3. The roof light is a relativley easy job to replace, (WAIT FOR A GOOD DRY FORECAST) undo the screws on the inside facia and remove, then up on the roof tease the outer frame away from the roof whilst inserting a plastic cooking spatula or similar non scratch item between the roof and frame to break the seal. If the roof light has been sealed previously with a oil based caravan mastic then it will tease off easily, but , if it was sealed with the ever popular Sikaseal 221 which is a flexible sealer AND adhesive you will have to cut the sealant with a sharp knife to break its hold. New roof lights are cheap enough and are about