KitchenAid A-9 Electric Burr Grinder "acorn nut" Questions

I need to order the acorn nut for a kitchenaid A-9 burr coffee grinder I found this while searching for shear pins http://www.partselect.com/PS984110-Whirlpool-9707016-Nut-Acorn.htm

...the grinder and parts? - Chris. Search online for "Kitchenaid 8204548" that's the parts list. It should take you to a Sears page with the parts you need. The part number for the Acorn Nut is

acorn nut in the center rotate. STOP. Back the assembly back until the nut stops rotating. That is ZERO. You can install the bean hopper with the zero facing the mark. You can also move the assembly a

I am trying to dissasemble my A9 grinder to clean the burr mill. The acorn nut on top doesn't budge. Is it reverse threaded or just tight? Left hand threads.