Fisher-Price is recalling about 900,000 child safety seats because of defects that can make them difficult to buckle or allow the shoulder belts to move out of proper position. The National Highway Traffic Safety Administration says the recall involves three models of safety seats manufactured by Fisher-Price. About 424,000 model 9100 and 9101 seats made between February and October 1989 have plastic on the buckle shield that can break after repeated use, making the buckle difficult to fasten, the traffic safety agency said in a statement. Fisher-Price will replace the shields free. About 472,000 model 9101 seats made between February 1991 and January 1992 are being recalled because the shoulder belts can move out of their proper position. The manufacturer will attach a new part to prevent the problem. The third recall involves about 14,000 model 9104 deluxe booster seats manufactured between April 24 and Sept. 4. A red button on the buckle can come off, preventing the buckle from fastening. Owners may continue to use the seats but should call Fisher-Price to either refund the cost of that seat, replace it or attach a new buckle assembly when it becomes available. Fisher-Price's toll-free number is (800) 332-3457 for models 9100 and 9101, and (800) 432-5437 for model 9104.