Hiya, I'm enjoying recording bats with my audiomoths which I've borrowed from my college. I have two AMs one of them is recording fine. The other is producing wav files containing no visible signals. Both have been configured identically and contain the latest firmware. I tested both side by side by switching to default and jangling keys above them. One gave a strong signal, the other nothing. Scanning the forum suggests this may indicate a microphone problem. I don't think the device is currently damp - but am drying it out just to be sure. Any other suggestions? Thanks in advance.