Just changed my microphones protectors and it seems not to be whistling in automatic. See if it stays like that. Only changed them few months ago but have had a lot of rain in the UK.
Have a friend who has had the Naidas since they first came out and I ask him how often he changed his microphone protectors and he has said never. Can't see how he is coping. He has NHS aids and they haven't given us microphone protectors. I bought mine. Me being 26 y o and working is fine. He is 15 y o and still at school.