My understanding about the arc 4 is that as the battery gets used up the light will blink and decrease its power level to a level that the battery can handle. If your light is doing this with a fresh good quality battery then you might have a light that simply draws to much power. You mentioned that your light is a second. Possibly this is the reason yours is a second. I also own a second. However I don't have that problem. I beleive mine got demoted to a second because of color of the light. Still very happy with mine.
cheers,
zwf