Buick 2006 Rainier Maintenance Manual page 13

Pull the seatback toward you as you lift up on the lever.
The head restraint will automatically fold out of the
way when the seatback is folded down.
To raise the seatback, lift up the seatback and push
until it locks into the upright position. Push and pull on
each seatback to make sure they are latched securely.
Then fold the bottom seat cushion back into place.
The rear seatback levers
are located on the
outboard side of each
rear seatback.
To return the head restraint to the upright position,
reach behind the seat and pull the restraint up until it
locks into place. Push and pull on the head restraint to
make sure that it is latched securely.
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