not sure if you can make that statement... you could say the same for the rest of the wiring, its been there for a while, its good...yada yada.... Everything ages, connectors move/touch, insulation melts, wires break. It would appear that your gage cluster lost its "drive"... get a meter and check the voltage and grounds going to the panel. Although from your "radio on, panel on observation", indicates a lost voltage, you should check the stuff. Further, it would appear that the radio power is "feeding" power for other things or vise versa... which probably not good in the long run.
Having said that, take a look at the ignition switch "wiring" for loose/broken wires.