hinges need friction between the parts at the rivets that pivot them, I don't think powder coating would be a good thing ... the easy test would be a new set of springs, but I'd think the hinges are the problem
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics