G'day Dave
Forgive any errors or omissions, I'm doing this from memory - too llate to go to the shed now but I'll check tomorrow morning if I get time and correct anything I've missed then.
Pop the transmission cover (rear bodywork panel off by removing the bolt and nut securing the seat base. The tin work slides off. This gives reasonable access to the clutch/pulley bracket thing that you are referring to. There are a couple of slightly different variants of this thing. The early variant has folded sheet steel belt keepers around the pulleys and these are loosened or removed by undoing the pulley bolt at each pulley. The later variant has a welded pulley keeper arrangement that hinges open when the bolt on each side that secures it is removed.
There is also a welded style pulley keeper at the engine pulley. Loosen or remove this as required to remove/install the belt. Similarly there is a keeper at the deck pulley in the shape of a bent bolt that is loosened or removed for access.
To quote that infuriating meerkat, 'Simples!'
Hope this helps and let us know if you need more.
Cheers,
