Three problems related to front seat belt have been reported for the 1999 Ford Windstar. The most recently reported issues are listed below.
Seatbelt on passenger side (front seat) of 1999 Ford Windstar rubbed plastic sleeve (where seatbelt retracts down into doorpost cover) causing excessive wear on the plastics edge causing it to be rough and jagged, which caused 1/4" of fraying into the edge of the seatbelt which continues to cut into the belt with each use. There seems to maybe be some kind of defect with the design. The drivers side has a warped (not supposed to be like that) plastic piece above the belt which pushes the belt away from the edge of the sleeve (hard to describe), making it not rub against the edge of the sleeve, so no problems with the drivers side seatbelt has developed.
The front seat belts get lightly pinched between the interior door panels lower storage bin and the carpet on the floor. This can cause someone to think that their seat belt is on correctly when in fact it is not providing them any protection at all. The 12-18" of excess slack that is caught between the interior door panel and the carpet could allow a person to not be secured tightly in place during an accident.
When moving rear seat to middle position behind driver, there is no place to buckle the lap belt. In the rear position there is, vehicle is adverstised and owners manual shows that you are able to swap middle and rear seating. This is a serious safety defect.