MH Light Bulb Gone Bad?

I have used a 250W Sunleaves Pulsar Mini dual use fixture for my last grow. Started and stopped the whole way through with it from seedling to harvest. I started with the MH for veg and HPS for bud through harvest. No problem.

Since then I have tried 3 times and can't get the little seedlings to grow. I germinate as usual, keep the heat right and I use a plant heating pad to keep the seedlings warm. As soon as they peek out of the grow medium (coconut husks or "Cocoa Noir"...I've used them for 4 years now, so that isn't the problem) they start to droop and die. Is it possible for an MH bulb to go bad and kill the babies? Or can any of you come up with a different possibility?

Can anyone come up with an alternative that would produce the same effect? When I used T5 lights I didn't have a problem either, but I've switched to the 250W MH & HPS system for more yield.