I'm not having much luck over this one. I've even tried searching images to see if I could find one of similar design. It's not the usual circular shape, but one with three 'prongs' to take the planetary gears and a somewhat smaller clutch than seems usual.
I've 'bitten the bullet' and I'm going to go for a Bafang. Hopefully I'll get it to match with my present controller, but if not, do you know whether simply leaving the PAS unconnected allows it to function in a 'twist and go' fashion?