Radio lights do not turn on?

If none of them are coming on but all the other dash lamps work, it would be an internal problem in the unit itself. Unfortunately for that vintage you would need to either remove it and send it out for repair, or find a used one and swap it in. There were three options for that vehicle. Some of them can be replaced with aftermarket. For that you might want to look at Crutchfield and see what you can find as a replacement.

https://www.crutchfield.com/car/carselector.aspx?lp=%2fcar%2foutfitmycar%2fmycar.aspx