A few weeks ago I replaced the ballast in the double 40W fluorescent light fixture in the laundry room because of its dim lighting. I also replaced the two old tubes. It worked initially but then only gave a quarter of the light its supposed to. Hard to tell the clean from the dirty laundry under those light conditions. Finally today I got out my digital multimeter, took out the tubes, and measured the voltage at the sockets. Over 300V between them at one end and about 150V between the sockets and the reflector — certainly enough voltage to light a couple of tubes. I changed one of the tubes and now its working. Suddenly I saw the light: now I realize that box of "econo-watt" tubes I bought were the source of my dimness problems. This may explain the seemingly shorter life of the ballasts, too. Now I resolve to buy "brand name" tubes on sale rather than a box of no-names.