Metal Halide wattage for bulb and ballast

I believe that a 400 watter will blow your 250 fast. You have to keep them
matched.

As for the bulb not firing, clean the contacts and retry again.

I have a set up (400W) I bought off of EBay that came with a Ballast,
reflector and bulb. I set
it up and it worked great. Just the other day the light wouldn't fire. The
smaller part closest to
the socket sparked a bit as if trying to fire the bulb but didn't
succeed.
My question is
#1 is there a way to tell that a halide bulb is dead?
#2 Does my replacement bulb have to be the same wattage as the ballast?

I am guessing that you could add a higher wattage light but not a smaller
but is that right? The
ballast is rated for a 400 w, can I put a 250 in there? The 400 is awfully
hot.


Thanks,
Kelly