Troubleshooting 5s analog radar scanner

My system includes networked E120 classic MFDs (with SW version 5.69) and a 4kW 5S open array analog radar scanner. Several weeks ago during a fishing trip I noticed no returns when I enabled the radar which up until now had worked fine. Scanner antenna is rotating as it had previously. Tried adjusting gain and other settings without success. Removed, cleaned, inspected and reassembled cable connections, again with any change.

Can anyone provide troubleshooting ideas?

Are there specific screens in the E120 MDF to help troubleshooting ?

thanks,
Mike