This may seem like a crazy question, but I have to ask. I have an 04 Yard Machine, model 13A7660G752 with a 20hp Tecumseh engine. It keeps throwing the drive belt off the front pulley. I contacted MTD to find out what I need to remove the pulley and they state the bolt is a 7/16-20X1.25. I crawled under the mower yesterday and it appears that the bolt needs some type of spanner wrench to remove it and the pulley. Can anyone shed some light on what I need to purchase to remove the bolt and pulley? Thanks for your help.