I am a newbie to the truck club, and a newbie to my Suburban. I have a 1996 GMC K2500 4X4 6.5 L Turbo Diesel. I am sure I have the stock GM radio with a cassette player in it. At the top of the radio are six buttons numbered 1 through 6. On the top row is 1-2-3, and the bottom row is 4-5-6. The lights are out for button 2 and 5. How do you replace the lights in this unit? Please tell me I do not have to remove the complete radio!!