The Corbin Russwin ED6000 Tenion Sub Assembly 378F74 fits inside the cross bar. As the cross bar screw is tightened the Tenion expands and secures the cross bar. This is usually the problem when the latch bolt will not extend. The lifting of the cross bar is done by the hinge case spring, and if the Tenion is not tight, the cross bar will twist.
Corbin Russwin part #378F74