Larson storm door 37081032.221 0707-13

If you're lucky, you won't have to remove the bottom door expander. Open the door and simply slide out the old door sweep, then slide in the new sweep. If it won't slide, then it might be pinched in the track and you will have to remove bottom expander. You can do this by slipping a thin putty knife or screw driver under the track where the sweep is pinched and then gently pry it open. After that, you can slide out the old sweep and slide in the new like before.