Too bad it's not easy to switch bulbs. However; my experience with HID systems tell me that the module you mounted inside the fairing likely consits of a ballast (xfmr), igniter, and possibly a capacitor. I would suspect igniter or bulb first, capacitor (if one is a component) next. Sorry, sounds as though it just can't get the boost, to start. I doubt it will get any better. Try switching bulbs first.
I would have them send me a new ballast and bulb. Then after you change both out, send their faulty components back. That way you don't have it tore apart for days.

Industrial HID lighting will generally generate symptoms such as these after a couple years of operations. Installing the wrong type of bulb (mercury vapor, metal, sodium vapor) etc.. will also damage the igniting components, many of the bases are interchangeable. I wouldn't think this would be the case, as what was sent to you was a kit.
Of course this all assumes, your connections are good, and there isn't a wire pinched in the fariing housing.