The reflector on the inside of the light actually is held on by ball and socket type connections. This allows for adjusting of the reflector. They sometimes come loose. You can remove the lense off the headlight and make sure the reflector is snapped on. This happened to my car the first time I changed the lamp.

Good Luck

You might consider removing the whole assembly to see where it's broken and how you might fix it. (You could also replace with one from a yard.) Removal is pretty easy - after you disconnect the wiring harness for the lights, 1) open the hood, locate the snap-tab for the corner light, press and remove the corner light. 2) If you have headlight wipers, lift the cap over the shaft spline nut, remove said nut (10mm), and pull off wiper. 3) Remove the three (I think) 13mm nuts that hold the headlamp assembly in place and then ease the assembly out. One of these nuts is accessed from the corner light, which is why it has to be removed.

The lens, as noted by others here, is held on by springy metal clips. DO NOT try to clean the reflector - the shiny surface is vapor deposited, and has been known to wipe right off. Also, left to right alignment is done at the dealer. If you try it yourself you'll likely break the L-R adjusting mechanism.

With luck you might find something easy to fix, like a broken screw, or at worst find a way to (temporarily) fix the assembly with epoxy or Homeland Security tape.
--
David
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98 S70 T5SE // Black, misc mods (mostly lighting), red calipers
92 940GLE // Hella MicroDE foglights

> Is there a way to fix this, or do I need a whole headlamp assembly?

I'm sure you've found the source of the problem now. Good question as to whether it's fixable. You may want to consider removing the glass lens to get a better view of what may be loose or broken. The lens is clipped-on from the front side and not too dificult to remove.

Gerald C