You had better confirm the issue is within the assembly before you open the headlamps up. Remove the headlamp assembly from the car (three bolts - two on top and one at the bottom. you will also have to disconnect the company headlamp wiring loom). Then remove the bulb from the holder and reach in and try jiggling the reflector assembly around. If it moves the problem is internal, but this is very unlikely. And since its has multiple anchor points, I doubt it'd be as simple as a missing screw.