How do I clean the buckle on the Graco Nautilus 65?

To clean the buckle, place it in a cup of warm water and gently agitate it, pressing the red button several times while submerged. Do not submerge the buckle strap, and do not use soaps, household detergents, or lubricants. Shake out excess water, allow it to air dry, and repeat as needed until it fastens with a click. (Page 89)