I usually pull the rubber bumper stop out then use a big craftsman screwdriver to pry it on there. If that doesn't work, you can always pull the pedal assembly out to put it in. I have a couple of sets laying around and ALWAYS have to tie the spring to the pedals or it just falls out. With the pedals out, The floor isn't there to stop the pedal from releasing the spring. I hope you don't have to go that far to get it in though.