the powerspade is a simple beast, just use the manual for the engine, the cutting head on the powerspade is rivetted pressed metal, so not easily servicable, but these are still available on the internet.
I have the older aspera engined version with a solid cast gearhead, but if the gearhead is not seized then you just need an engine manual (when I got mine it was seized, it turned out to be the gearhead which I stripped down and got working.
Grendel