I have a 1992 Ford Escort Wagon. How do I get the drivers side automatic seat belt to work?

It work fine then it worked occasionally and now it doesn't work at all. It is the kind that moves forward when you open the doors and back over your shoulder when you close the door, you have to manually buckle the lap part of the seat belt. I am thinking it might be the motor. Where is that located. I am a little mechanically inclined but am not a mechanic, so the more info the better for me. Thank you for your time and help.
Mike