Usually there are screws on the inside frame that screw through to the outside frame pulling the two together. Do you have screws on the outside screwing into the inside frame? They are usually about every 6 inches.
Bill
Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.