Dunlop guitar wah pedals don't "spring back", there's no spring. The treadle is attached to a rack (a plastic rod with gear teeth molded in it) and the rack presses against a pinion that rotates the pot. There's a small piece of looped plastic (actually a cable clamp), sometimes you can adjust the treadle's resistance to movement by loosening the screw that holds the loop and pushing it towards the rack. Or sometimes people try to lube the rack and pinion and overdo it, leading to a loose treadle that won't stay in position. Obvious solution is to clean off any excess grease or oil. "They" state you need to lube the rack and gear in a wah, but it's not really needed, IMO. The rack and pinion are made from a waxy plastic called Delrin. A tiny dab of grease can help the treadle work more freely and smoothly, but too much grease makes a mess and attracts dirt and grit.
