Yes Andy. It sort of flexes its muscles before settling down to where the ATC thinks it should be. I spent some time fiddling with mine (as I described before) with the valve motor disconnected from the valve, ie with the little white disc taken out. You do have to take the whole Black Olive assembly off the car (but leave the hoses connected) to do this. Then you can watch through the windscreen and see if it turns. You can also test the motor by putting 12v over the two power pins. I'd be doing that before replacing the ATC brain. Also, there might be a fuse in that curcuit somewhere which may have blown if the motor was unable to turn when you first set it up if it was in the wrong position.