Were you ever able to fix this? Our vent light button assembly just fell in. I haven't had luck finding directions for taking apart the front face or buying replacement parts. As best I can tell, Sears recommends buying and replacing the entire control panel assembly (Part #: 5304491493 $263, plus labor).
http://www.searspartsdirect.com/model-number/79080373310/0583/0123370.html?searchType=modelSearch&q=79080373310&searchTerm=79080373310