1. Ensure that the vehicle is on a level surface and the parking brake is activated.
2. Locate the headlight adjustment screws. On a 1991 Lincoln Mark 7, there are two adjustment screws for each headlight, located on the back of the headlight assembly.
3. Use a Phillips-head screwdriver to turn the adjustment screws clockwise to raise the beam, and counterclockwise to lower the beam.
4. Aim the headlights so that the center of the beam strikes approximately 25 feet (7.6 meters) ahead of the vehicle, at a height of 2 feet (0.6 meters) above the ground.
5. Repeat steps 3 and 4 for the other headlight.
6. Once both headlights are properly adjusted, check their aim from inside the vehicle to make sure that they are correctly aligned.
