The problem started with an LN 250 watt MH ballast turning off one evening. I thought it had over heated, so I moved it out from behind the stand, let it cool, and it fired up again ok. It worked fine for a couple of days, but now it's out completely. I switch the wiring to another bulb to make sure it wasn't a bulb problem, same deal, it will not fire up. The ballast is about 1-1/2 years old, they should last longer than that right? Any suggestions? Thanks in advance.