I'll be demonstrating the process of how to clean your toddler car seat buckle with the Graco Nautilus three and one but the same process will apply to all Graco harness car seats infant car seats convertibles all in ones and harnessed boosters it's important to periodically inspect and clean the buckle in order to remove objects or debris that might prevent proper functioning let's get started first turn the car seat over and push the retainer through the crotch strap slot place the buckle in a cup of warm water and gently agitate the buckle in thirty-second increments until it functions like new pressing the red button several times while it's submerged do not submerge the harness webbing or use any soaps lubricants or household detergents warm water is sufficient to clean your buckle remove the buckle from the water and shake out any excess water allow the buckle to air dry and make sure that the harness webbing is completely dry before using it again if the buckle isn't quite clean repeat the process of placing it in warm water and agitating it now test the buckle it should fasten with a click reattach the buckle into the same slot beneath the car seat and recheck the harness for correct installation as detailed in your owners manual before using your car seat