Just about every parent will need to remove the straps from their child's car seat at some point. This usually involves a spill and the need to clean the entire car seat. However, if the straps of the car seat's harness need more than just a wipe down, you must replace them since submerging straps in water can remove some of the fire retardant material required by Federal law for your child's safety.
Remove the car seat from your car. Place it on a level surface that's easy for you to access and work around, such as a table.
Loosen the straps on the seat to the loosest setting possible, using the adjuster lever in front. Turn the seat around and find where the straps loop over the harness yoke in the back of the seat; the harness yoke is a metal plate with the two straps going into the top and a single strap coming down from the bottom. Slide the two straps off the top of the yoke; turn the seat so that the front is facing you, and pull the straps through the seat towards you. Remove the car seat's cover and set it aside.
Hold the buckle that is typically between the child's legs and cut the strap that loops through the buckle. Lay the car seat down and face the bottom of the seat. Find the metal strap retainers; cut the strap on each and remove the metal retainer. Set the seat upright, and pull the harness straps free of the seat. Remove the pads on the straps at the child's shoulders, chest clip, HUGS™ rubber pads that are under the chest clip on the straps and the belly pad; these will all be used with your new harness.
Put the car seat cover back on the shell. Turn the metal retainer clip on the new buckle so that the short side is down and insert it through the cover and into the shell. Turn the retainer clip under the shell so that it lies flat against the shell. Make sure the red button on the buckle faces away from the child and the buckle strap lies flat.
Turn the metal retainer clip on one harness strap so that the short side is down and insert it through the cover and into the shell. Turn the retainer clip under the shell to its wide position and pull on the harness strap. Check to ensure the strap stays in the shell and the retainer clip lays flat. Put the shoulder comfort pad, chest clip and HUGS™ rubber pad back on the strap ensuring that the strap is not twisted. Repeat for the other strap.
Insert the open ends of the straps into the appropriate slot in the cover and shell. Pull through the back, and reattach to the harness yoke. You may need to turn the seat upside down to get the yoke to fall through the shell and access it.