I've a door sensor that keeps playing up. Some days it'll be good and works properly, some days it'll decide it'll trigger and let the door stay open all day, and some days it'll stay closed and not work. I've uploaded pictures of the model, and I'm wondering if anyone out there has a manual or can tell me how to I adjust the settings on the device? I've tried playing with the two white screws in the blue boxes to see if that influences the way it acts. I can't yet determine what influences what. Pic below. Click to view full size! I've also tried loosening/tightening the copper and silver screw on the top part and sometimes it works, sometimes it doesn't. Click to view full size! Click to view full size! I've also noticed that the width of the sensor has decreased, so definitely I've triggered the settings somewhere. I think it's an infra red sensor as there's a black cover that completely covers the front of the device. Many thanks in advance!