Ford Mercury Villager 1997 Owner's Manual page 323

Headlamp bulb replacement
Installing the headlamp bulb
1. With the flat side of the bulb's plastic base facing upward,
insert the glass end of the bulb into the socket. You may
need to turn the bulb left or right to line up the grooves in the
plastic base with the tabs in the socket. When the grooves
are aligned, push the bulb into the socket until the plastic base
contacts the rear of the socket. Do not touch the glass with
your fingers.
2. Slip the retaining ring over the plastic base until it contacts the
rear of the socket. Lock the ring into the socket by rotating it
until you feel a "stop."
3. Push the electrical connector into the rear of the plastic base
until it snaps, locking it into place.
Maintenance and Care
319