If its the model i am thinking of, look at the sides of the table near the top. There shoud be separate pieces of trim that are approx. 4-5 inches at the center and taper off at the ends. At first appearance they appear to be just decorative. these panels are covering access to the rail bolts.
To remove them you have to slide them up, then lift the bottom out. These panels have some foam behind them and usually get stuck. First give them a hit with your hand all alog the panel to free them up. Once they are free, you wil slide them up and side to side to remove.
once the panels are out you will see some 9/16 nuts. You only need to loosen them. They are securing a metal plate that will rotate 45 degrees, that will allow the rails to lift. The ends are similiar but use a little different
plate.
Please post pics if you can.