Having measured the incubator temperatures with a thermometer I trust, the Suro 20 reads about 0.1C higher than the thermometer. The difference for the Brinsea was closer to 0.3C (also higher), so I’ve turned up the temperature on that a tiny amount.
To see if it reduces the weight loss a little I’ve closed the vents slightly, my thinking being that if moist air finds it harder to leave the incubator then less water will be lost from the eggs to that air over a period of time. I’ll see how it looks towards the end of the week. I’m not that worried about it at the moment as long as it’s within reasonable bounds by the start of the third week.