FINALLY found and fixed the issue preventing adjustment of the headlights on my '04 Sport Trac! When I bought it a year ago in August, the driver's side headlight hit the ground 10-15 feet in front of he truck, while the passenger side light pointed up at the signs and trees on the side of the road. Adjusting the passenger side light wasn't a problem, but I went too far. The driver's side light would never adjust no matter what I did. Driving in unlit areas was actually dangerous.
I finally saw that the nylon cone on the back of the light that is supposed to go through the header panel and get locked in place, wasn't through the header. The top of the light wasn't locked in place, so turning the adjustment screw did nothing. Turns out that cone was too big for the hole it's supposed to go through. The lenses are perfectly clear, so I didn't want to swap the light. The cone attaches to the light with 2 screws, so I swapped cones with an old light, and now I can adjust the headlights! What a difference!! I need to tweak it a little, but now I can actually see the road!