After sharpening both sides of the blade place it on the kits cone-shaped balancer. If one side dips below the other continue sharpening it until the blade rests level. Return the sharpened blades to the mower and reattach. If you have a torque wrench its a good idea to use it here. Often you need to tighten the blade mounting bolt/bolts to a specific tightness level. Typically measured in pound-feet your instruction manual should list these specs. For example my personal machine the Honda HRR216VKA between 36 to 43 lb-ft of torque is required.
Next you will change the oil. To lower oil viscosity and get it moving freely run the engine for a few minutes. Now shut the engine off and roll the mower onto a piece of cardboard or drop cloth. Close the fuel line (if your mower has one) and unhook the spark plug as before. Find the oil filler tube and remove its cap. Often the cap also functions as a dipstick.
Your Best Digs rated the Greenworks 22502 as the best electric lawn mower. The reviewer found this push mower easy to maneuver thanks to its lightweight design. He also liked that it was much quieter than the gas mowers he tested. However he noted that dumping the clipping was awkward since there was a crossbar in the way and he would have preferred it if the mower came with an extension cord. Greenworks offers the option of buying the mower with an extension cord for $30 extra.