I have an Apple Wireless keyboard (not the magic keyboard) which I love and use almost every day and it has been rock solid. It was working fine yesterday. This morning the Delete key has stopped working. Every other key works fine. I haven't spilled anything on it or sat on it or dropped it. I've changed the batteries for fresh ones, I've taken off the Delete key and cleaned under it (it was already pretty clean, no hairs, no crumbs, a little bit of dust), but I still can't make it work. Any help? I'm not a brilliant typist and it is pretty unusable without a Delete key.