Our 07C210P passenger seat would make a noise going over bumps. It was the latch used to swivel the seats. It was not seated snugly in the notch that holds it in the forward position. I rotated the seat 90 degrees so I could push down on the latch to slightly bend it downward so it would go deeper into the notch to be seated more snugly. That noise went away.
After swiveling the seat many times over the years, that latch gets bent upwards a little, causing looseness in te notch and the noise we experienced.