Time to turn the machine on its side to check the blade. If it's bent or cracked, replace it; otherwise, you need to sharpen it. "If the blade is dull, it hacks at the grass instead of slicing it," Gray says, 'and it makes the motor run harder.' First remove the blade — there's usually a nut or bolt that holds it in place. To sharpen, use a hand file or sharpening stone (available at hardware stores) and start with five strokes on each side of the blade, filing from the centre of the blade out to the edge. 'You're not trying to put a knife edge on the blade,' says Gray. "The point is to file down any nicks so there's a straight line across the cutting edge. If you need to file more than one-quarter of the blade's width to do this, it's time to replace the blade." It's a good idea to always have a replacement blade on hand, and you can use it as a guide for sharpening your old one. Take the used one with you to a hardware store or a repair shop so you get the right size.
Before reinstalling the blade, check to see that it's filed the same amount on each side. Place the tip of a screwdriver through the bolt hole in the blade. Hold the blade at eye level. If it tilts to one side, file the leaning edge more, until it doesn't tilt. Reinstall the blade and ensure the bolt is tight. Give the blade a spin with your hand to make sure nothing obstructs its rotation, and also listen for grinding or squeaking noises'this could indicate a problem with the bearings or obstruction in the motor, which means a trip to a repair shop.
The wheels on most lawnmowers are adjustable to control the height of the grass. For the first cut of the season, set at the highest level so you avoid stones and other debris left over from winter that might not be visible. Be sure all four wheels are at the same height, or you'll get a ragged cut.
Make sure all nuts, bolts and screws on the lawnmower are fastened tightly. Working from the top down, check the fasteners holding the switchbox together and to the handle, those securing the handle to the body, any holding the housing down, the grass catcher and those on the wheels. Check all fasteners periodically over the season'the vibration of a lawnmower during use may cause some to come loose.