Buick 2004 Park Avenue Owner's Manual page 349

1. Buckle the center passenger position safety belt,
then route the safety belts through the proper slots
in the seat cushion. Do not let the safety belts
get twisted.
2. Slide the rear of the cushion up and under the
seatback so the rear locating guides hook into
the wire loops on the back frame.
3. With the seat cushion lowered, push rearward and
then press down on the seat cushion until the
spring locks on both ends engage.
4. Check to make sure the safety belts are properly
routed and that no portion of any safety belt is
trapped under the seat. Also make sure the seat
cushion is secured.
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