The entire spring system, from the shoe springs to the anti rattle springs on the rods act in unison to return the brakes. Either your springs are broken, missing, in backwards, bad repro return springs that do not fit, or there is friction on the wear points. Probably it is a combination of several or all of the above. Wear points to check are the cross shaft bearings, which get gummed or rusty, all clevis pins can be rusty or gummed up with dry grease and dirt, and the pedal shaft could be worn excessively, or gummed up. Internally, the wedges, cams and shafts could be gummed up. The easy accessible things are the clevises, cross shaft, pedal shaft and anti rattle springs. I'd start there by cleaning all moving joints and oiling them, as well as replacing the anti rattle springs in the correct direction ( facing away from the cross shaft) with good ones that fit properly. Many repro springs are junk and do not fit the upset on the rods. Brattons makes the flat style ( pre 31) that fits. Some other vendors sell Brattons springs too so you can ask them if you prefer another dealer. The 31 coiled springs generally work better, but I have seen repros of those that do not fit as well, so buyer beware. As you will discover, there is an after market return spring that is commonly used in this situation as a quick fix, but be aware that if your brakes are done correctly, the pedal returns on its own quite nicely. What Keith says about the floorboards is common too.
