Use a metal pry tool or flat head screwdriver to lift out the spring-loaded hinge

The spring in this hinge makes it difficult to reseat during reassembly. The easiest way I found to replace it was to fold the arm back into the closed position, and then grab across the top of the hinge with the very tip of a pair of needle nose pliers, using the pliers to rotate the hinge into position and press it down into place.