A buddy of mine has a 99 XLT and is having a problem with the lights in his radio. When I say lights, I mean the display of the volume, the clock, etc. The lights work when he is playing a cd, but when he puts in a cassette, the lights go out when he turns the key off and then when he starts the truck again, the lights still remain off. We think it might be a small bulb blown. If it is, how difficult is it to fix? Any info is well needed.