I have a 24" dual-bulb fluorescent light in the kitchen. Recently, both bulbs became extremely dim. Because they were relatively new (less than 1 year), I thought the ballast had failed. I matched the T numbers, wattages and other specs to a replacement unit at Home Depot and installed the new ballast, but retaining the original end caps. I also replaced the bulbs, on the "in for a penny, in for a pound" theory. When I repowered the unit, it is just as dim as before. Thinking I had purchased the wrong lumens bulbs, I recently bought the highest lumens I could find (1075) "daylight" 20W bulbs. No change. What have I missed?