Can a defective bulb cause a ballast to overheat?

Basically I have the adjustawatt digital ballast, its been running really hot the past few days and the seller told me to return it for a replacement, I was using a 600w dual spectrum bulb with it, anyway I just tried a spare.400mh bulb I had and its not running hot any more just warm like it used to do, do you think the dual spectrum bulb could of been faulty and somehow caused the ballast to overheat? The bulb was still working, it's just strange the ballast tempt is fine with the mh bulb.... Don't know if its worth returning or not?

A defective bulb can cause a ballast to run at a higher temp then normal but a bulb that works just as good as another of the same brand isn't something I'd call defective. As for your 400w lamp running cooler then the 600 is normal. The heat coming from the ballast is determined from the size of the load being connected to it meaning the higher the wattage of bulb and the higher the temp will be just like how your 600 is running warmer then the 400.