Sorry guys, seems like some questions slipped by me. Sorry for the late answers:
@theForge: sounds like a battery issue. I have had mine cut out as it died - with cold weather it can go quicker.
@davetheharris: yes, that's right, the NDS bearing play bolt should only be tightened till the play is gone.
@elag: just called you, on it, hopefully we'll resolve it shortly.
@GregW: I have the Duotrap on my Speed Concept and just use the speed magnet. It works fine with the power2max. I am not sure what the Garmin would record if you had the cadence sensor there, too - they can answer that better, sorry.
official power meter of Movistar Team