S60 driver seat stuck in up position

The rear most part of my driver side power seat is stuck in the highest position. The front part works fine. I can move the seat forward and back. The seat back works fine. When I press the button to move the rear part of the seat down, I can hear a click. How do I troubleshoot?

 

Here is how I resolved this problem. I removed the switch panel. The motor behind the panel has a wire connection on the top that had become loose. It looked like over time the wire was being pulled away from the motor (there was almost no slack in the wire to accomodate the movement of the seat). I cleaned the area and pushed the wire connection in tight. To help keep the wire in place, I wrapped two plastic wire straps tightly around the motor and wire. The seat now works!