What size wrench should I use to remove the blade-securing bolt on my unit? The most suitable size wrench to use to remove the bolt securing the blade on your MJ402E would be one measuring 1/2 an inch. Related articles What tools do I need to install the SharperBlade? My Hover Mower is not operating properly, what do I do? What are the 7 height adjustments for the MJ403E Mower? Where can I find replacement parts for the Sun Joe Mow Joe MJ401E Lawn Mower? MJ401C-BLD Replacement Blade