Use a large adjustable spanner and turn it anti-clockwise. It will turn, but it may need a tap on the spanner with a hammer to make it move initially. Hold the unit firmly, get the spanner securely on the nut, and tap the end with a hammer to get it turning.
You may want to enlist the help of a friend if you don't have at least 3 hands.
When you service the unit I would advise the use of a tub of clear silicon grease. The amount of grease in the service kit is too little, and black and horrible.
ChicksFan, May 2011
