older is better. more character on certain homes, solid walls, bigger rooms. better going for one thats altogether if your not good at diy. good luck with your search.
dont know it depends which way they snapped it in at manufacture. the lamp can be swivelled 180 degrees you see so it fits either way up thus putting sprung clip towards the front or towards the rear. when you slide the credit card behind it should pass further behind the sprung edge.
you can pull them out from the wing enough to slide a credit card behind, then push the spring loaded clip in and at the same time gently ease out. the end will pertrude out. careful though as only one end of clip has give whilst the others fixed.