I have a 2007 Silverado LTZ equipped with the factory sunroof. Every time it rains a little there is some water that comes out of the map lights and is damp under the driver side sun visor. I have checked the drain tubes and blew air in them with an air compressor. There is no blockages in the drain tubes. Any help would be much appreciated. My truck is no longer under factory warranty so I will have to repair myself. Thanks.