Clip+ FM Radio volume problem

I have exactly the same problem - I had my Clip+ replaced because the clip broke off and the entire player had to be replaced as the clips don’t come off!  While I was waiting for the replacement, I was using my older Clip, and when I used the replacement Clip+ today for the first time and was listening to the radio, I noticed the volume fluctuations you described - these are NOT present on the older Clip.