The first bulb that blew was the same one that was in the sled last year with no problems. I replaced with a name brand Osram bulb and it blew also. Is it possible the voltage reg I bought was bad right out of the box. I did get it from my local Skidoo dealer though. Last year I had no problem with lighting but my electric start didn't work. It would blow the main 30 amp fuse when I tried to use it. This year I traced it to a dead short in the voltage reg when I measured the red wire to ground. I replaced the voltage reg and now the electric start works perfect, but now blowing headlight bulbs. There are four wires coming out of my voltage reg. 1 red, 1 yellow, 1 yellow with black and 1 black. The red is power, the black is ground and I believe the yellows are for lights and accessories. Can a voltage reg be metered out and checked if its good. I just don't want to buy another one if its not the problem. Electric parts cannot be returned.