I have gone through 3 different rear lights.. all have the same issue with the arch leds not working. It isnt permanent -- meaning sometimes they are off, sometimes they work fine. I have also had the same issue on the front lighted T and have replaced that 1 time. I LOVE the look, but in hindsight wish I didnt have this mod due to all of the grief it has caused..
This concerns me a great deal. I can't imagine why you've been a victim of several erratically performing light Ts. I'm going to share this with Oznium to see if we can determine what's going wrong. We've had very few problems and you've seem to have borne the brunt of them.