Sears recommends replacing dull mower blades on its electric lawn mowers rather than sharpening them. Blade replacement is a bit different than for a standard mower. The blade adapter that fits over the motor shaft will only attach one way. Failure to assemble the blade correctly can result in damage to the mower. Replacement blades are available at Sears.
Place the mower on its side with the grass chute pointing up in the air. Position the blade adapter over the end of the center motor shaft with the flat portion pointing away from the deck. The blade adapter looks like a T.
Line up the square key on the inside of the blade adapter with the groove on the motor shaft. Slide the blade adapter onto the motor shaft. If necessary, tap the adapter onto the shaft with a rubber mallet until it seats on the end of the motor shaft.
Position the blade over the adapter, with the writing on the blade pointing away from the mower. The top of the adapter has two raised lugs that fit into two holes on the mower blade. Position the blade as necessary until the lugs protrude through the holes in the blade, and the blade is sitting flat on the adapter.
Place the washer over the retaining blade bolt. Thread the bolt through the center of the blade and into the blade adapter. Hold the blade with one hand and tighten the center bolt with a socket wrench. Place the mower back on all four wheels.