Problem with 400 watt hps ballast help please....

Ok so i just bought three hps ballast but one of them won't "charge" up all the way, it lights up the bulb but cant quite get it up.. i tried trouble shooting by puttin a new bulb in but there was no change. does anyone have any idea whats wrong with it. its the light on the left side of the pics.. you can tell its not fully bright. any ideas are welcomed.... thanks again RIU

i'd send it back to the shop if you can. if you bought 3 of them and only 1 has this problem i would think its a fault with the ballast

it was craiglist... i guess i'll just have to but another one...

yeah its ballast bro, but could also be one of the components inside, capitictor, internal wiring, bad spelling, etc