So I waited until the next day, then re-applied the spring to the hinge. The joint held. I gingerly tried prying the cover open, figuring that the leverage would break the joint if it was going to break. I proceeded to get more and more daring with it, finally holding it wide open and letting it snap shut, which is what you do when pulling the hose out. It has held fine for several weeks now, in regular use.
Similar techniques apply with other materials, such as brass, wood, etc.
My first test of Cyanopoxy was on some felt chair pads that defied all attempts to adhere to the nylon feet of some kitchen bar stools we use here all the time. I took the Cool Chem prep material called CoolChem Poly Treatment 311 and brushed it onto the nylon feet. I took the felt pad, gently misted it with the spray, and then applied it directly to the nylon pad, holding it in place for a few seconds. I also allowed this to set-up overnight, and the next day tested the bonds, firm as a rock. For my first test, I took a piece of Delrin sprue from a set of Atlas handrail stanchions.