I don't hear of those breaking too often! I would start by removing the bolt on the to of the fork shaft that comes up through the bearing. You'll need something to hold the remains of the shaft on the lower end. With the need of replacing the fork this might be a good time to look into Flex Forks.
You can find all the manuals you need for your unit on our website hustlerturf.com. On the bottom of the page click on the link for manuals and then find you model number.
Hope you have a Merry Christmas,