No, nothing missing, that plastic housing is set up to use the throttle advance starter lock out, but perhaps that engine was manufactured before the interlocks were mandated, or someone may just have removed those pieces. Nonetheless, the interlock/lock out pieces have nothing to do with the starter failing to rewind. Is this a condition that has suddenly occurred, or did you just buy the engine? You can certainly try to thread the rope around the pulley a few more times, but you will need to remove the rope from the rewind handle to do this.