Dismantle Hoover w/machine drum?
 

I'm trying to give a Hoover clothes washer (top loading) a clean out,
and need to remove the 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!