Heathkit T-3 signal tracer help

Would appreciate another set of eyes/brains, on this signal tracer phenomenon. I got one of these going. Been great. But I have a question. The unit is a kit build, no mains fuse, 2 prong similar blade power cable. When I plug the unit into mains, the optical magic eye indicator only responds with the heathkit T3 is antiphase plugged in. (Dmm in AC, across the T3 and a grounded device, shows mains potential across units) So with mains polarity aligned, T3 doesn’t illustrate... Read more