I worked it out! Apparently I was confused as to which sensor was which. Thankfully my two-bike wall rack holds my Gunnar high enough so the sensors are at my eye level and finally figured out which was which. It doesn't make a sound when things are aligned properly, but there is a little green light on both sensors when all is aligned and working properly.

So that is two things I've managed to fix myself this week with a little TE advice - no transporting bikes to LBS needed. YES I love my LBS, but would like to reserve their time to things I can't do myself