Yep, new cyclone top needed! You could get lucky and ebay or mvacs will have a purple one for sale, or buy a silver one from mvacs and dont worry about the colour!
Take the bin off, undo the 3 security torx screws and pull the top off. Swap the bin release rod over (a non security torx screw) and fiddle the rod back into the bin release assembly at the bottom. check the rubber seal is present on the new bin top, if not then swap the one from the old one on. 3 screws back in