I recently bought a Contour +2 as a helmet cam. I like the video quality but there is a lot of wind noise from the internal microphone so I want to use the external microphone inside my helmet. When I plug in the external microphone using the 3.5mm to 2.5mm adapter cable, I'm still getting audio from the internal microphone. If I turn the mic sensitivity on the internal mic down to zero and the external mic up to maximum, then I get no sound at all. I've already had the camera replaced and am seeing exactly the same problems with the replacement. Has anyone got any experience with the external mic on these cameras?