Make sure your bulb is seated correctly. Take the bulb out, make sure its seated, then make sure the plug itself is seated correctly. Also, make sure the pins that hold the housing are going through the brackets...sometimes I dont put the headlight in all the way and it misses one of the holes if Im in a hurry...ummm...other then that, I dont know
You can adjust it with a wrench/socket with that adjustment screw...but I dont see why that would get messed up...also, on the back of the light, make sure its tight (where the rubber square pieces are)...I had to tighten mine up because the bracket was loose which caused my headlight to wiggle left and right