Digital ballast question

I have a 250HPS light, and sometimes it didn't turn on when its supposed to. I'd go check when the light was supposed to be on and it would be off. A quick click off and on again would fix the problem. I'm 99.44% sure it has nothing to do with my controller. Is there something fixable on the ballast itself?

BTW, not sure if it has anything to do with the problem, but I'd notice slight variations of light output sometimes. Almost like with a regular lightbulb will dim for a second when some other device in the house gets turned on, but very slight effect. Is this normal for a digital ballast?

its defective the light out put should always be the same after ther warm up period, besides taking into account lumen degradiation, and you definately shouldn't have to toggle back and forth to come on, you need a new ballast or lamp
sometimes if the lamp gets messed up it can cycle which is go on then shut off sometime it varies between cycles, remember with HID lamps there is a cool down period before the lamp will relight, unless you are using pulse start lamps

just re read your post HPS are pulse start, but HPS lamps can cycle all the same just dont have near the cool down period