Garmin Edge 830 - Speed Sensor drop out and reconnect.

Hi All, 

Has anyone had any problems with the garmin speed sensor/830 combination? Mine keeps dropping out and then reconnecting every few seconds. Ive done a firmware update and a fresh battery on the sensor - but wondering if the sensor just gives up after a while and I should get another one? 

I had no issues with the same sensor and the garmin 130 for the previous 2 years, but recently updated to the 830 (about a month prior to this problem).

Any suggestions?