Hello, We have had the cat flap for several years & it has always worked perfectly (with our chipped cat). But now - all of a sudden - it no longer recognises the chip. I have already - cleaned the outside - tried re-recognition as well as going back to the factory setting. > no change Question a) Does anyone know this problem? b) How can I open the frame cover so that I can clean it (maybe the scanner is blocked?)? 1000 thanks.