How to Troubleshoot a Black and Decker Lawn Mower MM875

Avoid overheating the motor by using the proper gauge extension cord for the mower. Use an extension cord of 14 gauge or better in any length that's less than 100 feet. Prevent harm to the motor's longevity and power output by not combining extension cords or using any cord that exceeds 100 feet in length.

Check the electrical outlet being used if the mower fails to start. Test the outlet by plugging in another electric tool, like a drill. Reset the circuit breaker or replace the fuse for the outlet, if necessary. Transfer the drill or other electric tool to the female end of the extension cord to confirm good cord conductivity. The mower should run if the drill does.

Adjust the deck height if the motor slows while cutting. Disconnect the extension cord, and clear the discharge opening or clean the underside of the deck. Cease mulching, and connect the discharge chute if clippings continue to clog the deck. Mow in drier conditions if clippings clog the bag or if clumps of clippings are discharged.

Inspect the grass blade tips after mowing for poor quality cuts. Sharpen the blade with the drill and sharpening stone if the grass exhibits jagged edges or shredding at the tips. Investigate mower vibrations by inspecting the blade for chips, cracks or looseness. Follow the manufacturer's guidelines for removing and balancing the blade if no defects are visible. Consult a Black and Decker approved service center if vibrations persist.