Nearly 800,000 child safety seats produced by Dorel Juvenile Group are being recalled due to safety harness problems, the National Highway Traffic Safety Administration announced Monday. The recall covers booster, convertible and infant seats made by DJG of Columbus, Ind. At issue is the harness locking and release button, which does not always return to its locked position. This can allow the harness adjustment strap to slip back through the adjuster as a child moves around in the seat and results in a loose harness, increasing the risk of being injured in a crash.