Mercury 1996 Sable Manual page 194

The third seat in a wagon
3. Remove the cargo cover. The cargo cover
must be removed or the seatback cannot be
locked in the upright position.
4. Lift the remote latch release on the left side
of the well and fold the remaining floor
panel toward the front of the car until it
latches. Make sure the seatback is locked in
the upright position by pushing forward and
backward on it.
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