I decided to finish off the current career and restart per my note above. However, on return to Midway they offered me a new radar, one attached to the periscope, so of course I took it to test it out.
Despite have the SD "on" and pressing the SJ "on/off" button, neither of the radar screens were operative, and I failed to pickup a target only 5.2 miles off the starboard bow. The boat was on the surface. I even raised the periscope, but that had no impact.
There is an "on/off" apparently moveable switch on the radar units, but although it is lit when the cursor passes over it, it will not operate. So now I have a new radar, but no radar? Am I missing something, or as has been shown many times, did I fail to read and follow instructions?