My bathroom has a fixture for twin 48" fluorescent bulbs. About every six months, the bulbs start to go bad. At first they will only come on about half way, and they flicker dimly for a few seconds before reaching full brightness. After a few weeks they just stay dim no matter how long they are on.
I have already replaced the ballast in this fixture, thinking that might help. No joy. I have replaced the bulbs twice a year for four years. I use the same bulbs in my other bathroom with no issues. Any suggestions?