OK, I have PFO dual 400W ballast and one of the light bulbs dimed and barely working , so I changed light bulb for new one and its same story. So do i need to replace my ballast?
With the power unplugged, and very carefully, take a look inside at the capacitors. If it has bulged (there was a rach of this) or leaked, it will need to be replaced. BEWARE! Cap's hold juice and discharge fast long after they are unpowered. If you don't know what you are doing, leave it to someone who does. D