I was today in my office and the oxymeter was still alive. Nothing strange on that, except, that it showed 72% of oxygen in the air. There were around 13 mV out of the cell. As you can see on the image below, it was calibrated on around 4 mV (maybe less as there was constant decrease in the time)... The cell is out of date and out of order, of course. But i'm surprised with the voltage! And it is quasi imune to oxygen change. Do you know something about this type of oxygen cell failure? (Yes, i checked the output with voltmeter),