Replace cable on Hoover Whirlwind?

I need to replace the mains cable on my Hoover Whirlwind bagless vacuum cleaner. It appears that the top part of the main chassis is a separate part from the bottom but I cannot work out how to remove it.

I found two screws at the top rear and another behind the pipe stowage area in the handle. Undoing these, the handle moves very slightly but still cannot be removed and the top section is still anchored to the bottom.

Can anyone explain how to open up this beastie?