Spirit Rear Seat Locks

I just bought a 1991 Spirit from an elderly lady. The rear seat latches that open the seatbacks to the trunk seem to be stuck in the locked position....the latches only come up about half-way. Each latch has a lock setting in front of it, and the lock-slot is in the horizontal position. I have used a large-blade standard screw-driver to try to open the lock into the vertical position, which is suppose to de-activate the lock function ( as I've seen in other Spirits), but no matter how hard I turn the screwdriver clock-wise, I can only get the lock-slot into a 45 degree position, which does not unlock the latches. I have refered to the owner's manual, but there is nothing in there to describe how to unlock those seat latches. Anybody out there have any suggestions? Thanks