Which part is broken the inside that fits into the reflector or the fingers that hold the ball joint? Those fingers hold the light stable as the 3rd point of contact in the housing because the only other thing holding the reflector is the adjustment screws.
1. If you broke one of the fingers, finish your retro, put the lights back together with the metal ball joint in the white tab and epoxy the finger back on. If you ever have to take it out again expect it to break.
2. If you broke the base, just epoxy it back on.
3. Try a local NAPA. When I found that my adjustment tabs were stripped I checked NAPA and they had a listing for tabs inside of the headlight. See first post if yours are messed up aswell.
To take the reflector out of the socket loosen the adjustment screws evenly. You'll see once the outside of the lens is out a little farther than the other side with the ball joint on it. Now it's time to take the ball joint off, use both thumbs on either side of the clip and push out.
Hope this helps