Dismantle Hoover drum?

I'm trying to give a Hoover clothes washer (top loading) a clean out, and need to remove the inner drum.
But, I can't see how to remove the agitator, which I presume needs to come out first.
I've stripped it down as far as I can at present, and can see a (fragile-looking) plastic epicyclic gearbox and a brake mechanism at the bottom end. There's an Allen bolt associated with the brake, but loosening it didn't seem to help. I daren't whack the plastic parts!
I gather this is a common method of transmission, so there must be a fairly standard way to dismantle?
Hoover Model A6830 ("500"), made in Australia.
Any advice gladly received!