The other symptom I've noticed is that everytime I stop to calibrate, I get a number from one of 2 narrow ranges. eg. If I calibrate 4 times on a ride, I might get calibration numbers of: 9,8,16,9, or 9,16,17,9, or 17,8,8,16, etc...
(if I calibrate multiple times in a row, then I get a consistent number, the number only changes randomly if I've ridden for a bit)
I also tried putting put a second power meter on the bike (C1 chainrings) to compare and they would often disagree. Sometimes the G3 would read higher, sometimes lower (usually somewhere in the +/-25 watt range)
To me it seems like there is something wrong with the power meter, but Saris is telling me that it's behaving fine. They say that if it's giving a calibration number between -30 and +30, then it's working fine. My understanding was that unless there was a substantial temperature change, I should be getting a consistent calibration number, is this wrong?