Bought a 95 LS400 in great condition about one year ago. Only one owner, perfect service record. The back light on the radio display began to come and go, and is now gone (dark). I can detect a fain glow when it's dark when the headlights are turned off, so it is still getting power. The display for the heat and A/C panel is working fine. The dealer says I have to replace the whole radio for +/- $600. Any advice?