Mitsubishi ECLIPSE Owner's Manual page 51

Seat and restraint systems
2. Grasp the latch plate and slide it up the webbing so that it
easily pulls across your body.
2
2-16
3. Pull the seat belt out slowly while holding the latch plate.
Push the latch plate into the buckle until you hear a
"click". Pull up on the belt to be sure the latch plate is
locked securely in the buckle.
NOTE
If the seat belt locks up and cannot be pulled out, pull it
once with force and let it retract all the way.
Then, pull the belt out slowly once again.