Shut off all power to the pump by unplugging the pump from the wall outlet or shutting off the breaker powering the pump. Twist the unions located on the pool plumbing going into the pump counterclockwise by hand to free the pump from the hard plumbing. Pull the pump away from the plumbing and set the pump on a flat surface away from obstacles to provide a large area in which to work.
Unscrew the four bolts located on the outside of the wet end of the pump -- the end previously attached to the plumbing -- using a socket wrench. Most Hayward pump bolts are size 9/16-inch. Pull the pump's wet end to separate it from the motor portion of the pump system.
Locate the diffuser -- a small plastic pump piece that is usually cone-shaped -- covering the impeller and pull it off the pump's seal assembly. Remove any large debris such as hair, leaves or rocks caught inside the impeller using a small screwdriver. Do not apply unnecessary force to the impeller with the screwdriver or warping and other damage to the impeller can occur.
Slide the cone-shaped diffuser onto the shaft until it fits snugly up against the impeller. Position the motor next to the wet end of the pump. Align the bolt holes located on the wet end of the pump with the holes on the motor portion of the pump. Insert the four bolts previously removed into the bolt holes and screw them in securely with a socket wrench. Take the pump system over to the pool's hard plumbing and attach the pump to the plumbing by screwing on the unions tightly.