HIDs -- Symptoms of a Ballast change?

I have a 2004 Prius with HIDs and had done a bulb change 5-6 years ago. At the time i had issues with periodic non starting bulbs and thought at that time I needed a ballast change with the new bulbs. Low and behold, i did not hav e to turn off and on headlamps any more. I have been noticing a bulb color change to a slightly rose colored hue. Cycled on /off and upon a 30 sec. shut down and re-start the color starts out white but after 15 sec. it goes to the unwanted temp. I notice that the lamp's focus seem to change and stablilize with the rose color/ temperature.

It is the "flickering" that has me baffled. DO I need a ballast change - or a bulb change only?

Thanks for your input.