The spring in your picture is a old car drum brake spring, throw it away. Picture 2: at the far left end of the sliding part there is supposed to be a small spring connected to the end of a cotter pin. This is a factor spring to pull the pto all the way forward and stop it from spinning when disengaged. Also the part that you rock with your foot should have a decal that shows the proper placement of the 2 wire guides. The wire guides should be 1/8" away from the belt when the pto is engaged. The worn belt is probably from the wire guides rubbing on the belt.