Moving parts? A door axle sitting 12" above the muck and a treadle that if properly designed cannot collect litter or much, 1/8" x 3/4" flat bar on edge with a narrow step on the end. Not going to gum up and only two moving parts, the treadle and the door. Now those wide step monstrosities used on the Chinese made Grandpa feeder and the clones, yeah, five or six joints or pinch points and a wide flimsy treadle that is more designed to appeal to the consumer than actually work. And if the treadle door is spring loaded not even a large rat is strong enough to push the door open. The Chinese made feeders? Yes, a small rat or ground squirrel can simply push the lid up. Not so with a property designed feeder. The wooden treadle feeders are just clones of the Chinese made Grandpa feeder, poor design, no counterweight, no spring loaded door, yeah critters can get into them easily.