Aeg dishwasher ESL63010 upper spray arm

May sound a stupid question but how do you take the top spray arm off on these dishwashers. I’ve got one that’s split and notice the Venturi and arm can be bought separate like most but only having a quick look couldnt figure out how to detach it. They usually have the usual collar you twist or raise the arm and twist but I just couldn’t manage it.
Probably simple when I go back but I was just wondering if anybody knew.

Thanks

Nick