Ballast problems

[bluetang]

I have HQI lighting above my tank. I recently changed all the bulbs.
I have 1 single 250W Ice Cap balast and 1 Double 250w Ice Cap ballast.
The single is lighting up the bulb alot brighter than the Double balast is lighting up the two bulbs. I thought maybe it was the bulb so I changed them around and still the same thing. Do I need to get the ballast tuned up???
Or should I bring it somewhere to get fixed? If so Where?
Has anyone experienced the same thing?

Rob