How do I take the back off my Tefal Superglide Iron to gain access to the S?

How do I take the back off my Tefal superglide Iron to gain access to the swivel joint on the cable. Problem with iron intermittent breaking of supply line - iron going on and off when cable is moved. Maybe bad connection or damaged cable. Have removed screw from back [plate but cannot remove plate. Do not like to use foprce for fear of damage. Help!