On the past two rides, my beloved Polar 720 power option stopped recording power properly while recording speed and cadence properly. It happened suddenly midway during a ride when the power values reported dropped on average to only 30% of the actual value. It also report pedaling index as around 70% (usually 25-30%). It has done this ever since. Since I have a 2nd complete power unit I was able to trade components and was able to identify the magnet unit as the main problem. My S-720 unit works fine with the the 2nd unit. I mailed it to Polar for servicing and they send it back withou being able to find anything wrong. I reinstalled it and things were fine for 20 miles after which the same problem recurred. Does anyone have any clue what's going on and what I could try? Thanks
