Intermittent dash lights and radio

I'm going to pull the speedo cluster this weekend and check everything. An update on the symptoms: the dash lights don't work at all now when I turn on the headlights - all I see are the speedo, tach and other needles glowing red and the backlight on the odometer, as well as any dash indicator lights such as turn signals, CEL or air bag etc. when they are lit, otherwise none of the actual dash lights. This includes all the temperature control lights and the hazard switch light being off when headlights are on. The radio still works for the most part - it lights up when headlights are off but once they are switched on, the radio info displays but not the backlight. Also the radio is continuing its cycling on/off randomly and its doing this much more than previously - sometimes it works fine for my entire commute (15-25 minutes) and other times it cycles on and off repeatedly as I'm driving. I can't really see how this is an alternator or battery problem, as everything else works fine and the battery is charging and is starting the car fine, headlights work fine etc.