Lincoln 1999 Town Car - Manual (Page 171)

Do not remove lamp bulbs unless they will be replaced immediately. If a
bulb is removed for an extended period of time, contaminants may enter
the lamp housings and affect performance.
Replacing headlamp bulbs
Handle a halogen headlamp bulb carefully and keep out of
children’s reach. Grasp the bulb only by its plastic base and do
not touch the glass. The oil from your hand could cause the bulb to
break the next time the headlamps are operated.
To remove the headlamp bulb:
1. Make sure headlamp switch is in OFF position.
2. Open the hood.
3. Twist the plastic knobs and remove the protective cover from the back
of the headlamps. Lift the cover and pull towards the windshield.
Maintenance and care
171