The radar in my F16 viper suddenly stopped working so I began to troubleshoot. Checked the panel cfg and all the gauges appeared to be there. I checked my fsuipc. All appeared to be OK. I downloaded the panel and plane again and reinstalled everything.
Finally, after two days of troubleshooting, and just before I posted here asking for help, I made a new discovery about the gauge.
There's an on-off switch.
Doh!