I found the memo...

ResMed has observed that prolonged and
repeated use of an ozone device may eventually cause internal damage to a ResMed machine, leading to
an increase in motor noise

So that is probably what happened to me. Oh well, live and learn.

Now the bad news... The annoying whine has returned. This seems like the one downside of the Resmed, there are so many comments online about it developing a whining sound. I hope you get yours sorted soon! I have not seen many comments online about ResMed's developing a whining sound...I guess I ne...