My Hayward Superpump was seized when starting it up for the season, so I dismantled it to free the shaft and got down to a further layer than necessary. After removing a screw on the AO Smith 3/4 hp motor, I realize it can't be screwed back in and can't see what it connected to. Was there a nut holding it in place that's fallen into the impeller? What's the point of the screw anyway? A pic's attached to help this make sense.