Your probably right, but mine were sitting for about 10 mins from fully up to down then central with nothing happening.
I put markers on the wall where the light sat and after some tapping and wobbling the light beam moved down and then back up, I could see this as I was laying down the side of the car with my arm adjusting the rod. They moved very fast but didn't work most of the time. The lights are now up and I've removed the sensor to get me by.