hi have you tried removing the switch and carefully opening the case and cleaning the terminals inside as the get dirty from repeated use and sparks jumping as the switch makes contact. If the terminals are very dirty a piece of very very fine grit sandpaper or a womans nail board may be off some help. this may help you out
we do this all the time at work as i am a mechanic and some gloveboxes use the same style switch
John from JDS AUTOCARE, January 2011