Yes, all of the Greenfield models I've checked in the manuals have a disk-and-spindle that is a single part:
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Presumably the spindle is tight on the ball bearings it runs in, so it will need something like a light press load on the top of the spindle to push it out. Depending on how rusted on it is, you may need a pair of support plates and a split ring in between the bottom of the bearing housing and the top of the disk, to get it out safely. In the parts list I can't see any secret circlips that complicate the process. However it might be safest to ask a Greenfield dealer, or phone Greenfield's customer department, because it would be embarrassing and expensive to break the housing through missing a trick.