Tried to be as descriptive as possible in the title. When the snorkel gets to the top, the motor will come on only if I exert downward pressure on the top of the snorkel before pressing a ventilation button (High, Med, Low). Once I release pressure, the motor stops. With the motor off, I can hear a switch clicking as I press and release the snorkel. I've looked at some repair diagrams and see that these units have a "Ventilation Switch". My thought is that this switch is bad or needs adjustment. I'd appreciate any help. Thank you.