Headlight moisture

Just in case this is of interest to anyone, my 20yr old 2006 focus headlights were heavily oxidised and they both had moisture inside. White toothpaste, a lot of elbow grease, and then car wax did the trick for the oxidation. One of the headlights dried out naturally but the other didn't, or if it did a little, the moisture would be back the next morning.

The air vent was clear. I noticed the lenses would separate a little from the housing at the top corners and then contract back together. I've heard Permaseal was originally used. The thought of taking them apart and resealing was too much for me. So I removed the bulbs and dried it out. There was also moisture in the back bulb cover. I sealed the outside of the headlight with aluminium foil butyl tape. I kept pressing it in to ensure a seal. I also cleaned and greased the rubber seals of the bulbs back cover and indicator.

So far, two weeks later, the moisture has not returned. Maybe I got lucky, but I guess time will tell, especially next winter.