About 6 months ago I had to change some older style (larger diameter)
fluorescent bulbs (about 3 or 4 foot long as I recall) in my kitchen.
I have 2 pair and each pair are installed in their own housing. I
noticed even after changing the bulbs all around and plastic lenses
covering them, that it seems that the bulbs in one housing are always
yellower than the other (which is more white). Is this a ballast
problem? They seem to all turn on okay.