3X be there done that 3 times, first time burned out all bulbs, second time just as described above, third time last year buddies skidont. Completely quit. Had to stop and charge his battery from my sled several times to get back to trailer. (mine four stroke, I carry jumpers, sure beat dragging him back 70 miles)
Guess I'll find out also, got the same sled, same symtoms. I've seen the low lights, but the first time I rev it to 4-5k, it goes bright, and never fades again. Doesn't always do it either.
I'm leaning towards a ground issue for me based on the never dims again part once running. (Fingers crossed)