Good choice in switching bulbs working from one to the other. Process of elimination. So if left flickers, no matter what, it is not the lamps, it is something else....perhaps ballast, write down all your findings in detail that you tried, have them in front of you for when you call ATI tech support.Ok guys. Unit on the left side is flickering and right was fine. I completely switched all bulbs from left to right and the right to left. If left unit is still flickering it means unit is faulty. If unit on right starts flickering and left isn’t anymore, that means that it’s the bulbs that were faulty. I’m really hoping it was the bulbs. But one part of me hopes it’s not because then I’ll always be scared of ordering new bulbs.