Please post your reply again, I did not received any reply regarding my questin on the retractable ventilation system, Thank You.

When switch on, the right knob/control high/low of suction always catches , that prevent the panel to raise. Also sometimes when switch off, the panel "fall" suddenly. what parts need to be change? right now I just put a tape on the upper portion of the knob which won't last just to prevent it from catching. Please advise, Thank You.