Burnt out MH bulb or toasted ballast?

[Richer]

What are the symptoms of a burnt out bulb, as oppose to a toast ballast?

Last night I noticed that the light output from my 70w Viper 2 was much lower than usual. I thought that perhaps the fixture overheated or something so I shut the light off and let it cool off for an hour. Now when I turn the light on, the bulb refuses to light up, but I can hear the ballast humming and clicking (I assume its clicking because its trying to light up the bulb?). FYI, I bought this thing new 2-3 weeks ago, there's no moisture damage that I know of. The ballast is stored under the tank, and the whole setup is in the basement, so I doubt excessive heat is the problem.