Components of a typical rotary lawn mower. (click to enlarge)

1. Disconnect the spark plug cable for safety.
2. Use scrap lumber to wedge the blade into a stationary position so it won't turn when you loosen it.
3. As needed, remove the blade with wrenches and a gloved hand (for protection). Use a pencil to mark the side of the blade that faces down for proper reinstallation.
4. Inspect the rotary blade for damage and replace as needed. Some blades have a metal bar called a stiffener that also should be checked. If necessary, replace the blade with one as recommended by the manufacturer.
5. Use a flat file to sharpen the blade, filing only in one direction. Follow the original contour of the blade edge.
6. Insert a screwdriver through the center hole and hold the screwdriver to determine if the blade is balanced. If it is not, use a file to trim metal from the heavier (lower) end until it is evenly balanced.
7. Reinstall the blade, making sure that the blade is installed as it was removed for proper operation.
8. Reconnect the spark plug.

Service control cables:

1. Disconnect the spark plug cable for safety.
2. Remove the controller cover and loosen the locknuts.
3. Remove all slack from the cable, reposition the locknuts as needed, and tighten the locknuts.
4. Test the controller by moving it through the various positions and making sure it responds appropriately. If it doesn't, readjust it.
5. Reconnect the spark plug.

Replace the wheel drive belt:

1. Disconnect the spark plug cable for safety.
2. Remove the cover over the wheel drive belt.
3. Tilt the pulley toward the engine and remove the belt from the pulley.
4. Tilt the mower to remove the other end of the belt from around the blade pulley.
5. Install the new belt in the opposite order: around the blade pulley then around the wheel pulley.
6. Tighten the wheel pulley adjustment so the belt moves 1/4-inch when pushed halfway between the two pulleys. Readjust as needed.
7. Reconnect the spark plug.