I had my fluorescent work bench lamp apart today to try to stop an
annoying intermittent buzz from the ballast. It's a typical two 15W
tube with separate series inductor ballasts for each tube.

I was surprised to see a 4.7uF cap in series with one of the ballasts,
but not the other. I'm wondering why they would have put a cap in
series with only one ballast? The only thing I can think of is that
it might cause one tube to operate 180 deg out of phase from the other
to reduce flicker. The cap was shorted and I'm wondering whether or
not to bother replacing it.
Andy Cuffe