Under a different light...
Now that I've seen the video, what I thought was a groove on the dashboard earlier on, was just an optical illusion created by the shadow between the door and the control panel.
As for the plastic drum pulley... I've never seen one on Candys... I've only ever seen them on some Electrolux models, but maybe some Candys have it too: not the ones I've seen though.
I've been naughty too with my Hoover and took the back panel off once... the back of the pulley has a nut that can be unscrewed to replace the bearings, and another thread inside where part of the shipping bolts have to be tightened in (imagine the damage if one doesn't remove these before using the machine) but on yours it looks like a blind cap... does your model have a sealed tub or is it just a cover?