Left strobe quit working on my 2000 Ovation 29-0243. I swapped the right side over to left side, still no work.  Took the inop left side over to the right and it started working, which leads me to believe it is the wiring harness or the strobe power supply.  At this point, it is a black hole as I don't know what is inside the box or how the wires are tied into the airplane.  I did some research and there is a power supply tester, but it is $250 or so and I guess it tests the voltage and Polarity