Animation No 2 is more visible but I think the brushes do not move like that in real life?
As far as I have see, the arms only move to better follow the gutter or to get around obstacles.
Maybe there is an extra wiggle-mode if a specific spot needs to be cleaned (like oil spill or glass?) but I have never seen a sweeper operate like that.
But it looks funny so both animations are okay for me.
Maybe some colore elements like this would make the rotation even more visible?
The front pillars of the cockpit seem quite thick.
Usually in such vehicles they are as thin as possible to provide best visibility, also to the sides. (Compare to Flame's picture)