One side was dented on arrival and that could be be reason causing the grille (or “front filter”) to bend a little which gets in the way of the retractable cover arm. I had to straighten the grille a little in order to make clearance for the arm to retract without making any noise. It’s all fine. All these problems won’t affect its function. The dents can’t be seen from the front.
Overall, good suction and the design really help the air flow.