Bit of a necro post here, but I have almost exactly that Sadie in pieces on my workbench right now. Lid latch are three flip-over-pull-down style clips rather than the ring band that yours seems to be, but otherwise identical. Sadly, the thing was working perfectly until the roof leaked on it the other week and it developed a light coating of rust inside the tank... And motor.
The tank is fine. Hell, it could be replaced with a big paint tin if it comes to that. But the motor needs a clean and service. Which I'm able to do.. IF I can work out how to get the damn thing apart. It appears to be welded or fused together inside a galvanised tin looking can, and I don't want to just give up and cut it open if it turns out there's something dead simple that I'm overlooking to getting it apart.
Does anyone have any idea on this? I can post pics if required.