My Sena 10 worked fine on my older Arai helmet, but when I moved it to my Shoei Neotec, the audio wouldn't work once the mounting screws for the clamp were tightened down. I tracked the problem to a little bit of flexing that was caused by the shape of the shell. Since audio would come back if I pressed on the radio, it was clear that the connection at the pogo pins wasn't working right.
Here's how I fixed it -- the individual pictures all have captions once you click on them.