Another customer wrote to us directly:
Heat 1.1 litres of milk to 85 degrees, then cool to 45 degrees. Inoculate with 3 tablespoons of natural yoghurt and stir well, fill into the jars and set the clock to 9 hours.
Good luck.

It's very easy: Mix 1 small natural yoghurt and 1 litre UHT milk well with a whisk, pour into the 7 jars of the yoghurt machine, switch on overnight, take out after 8-10 hours, put the lid on and refrigerate. Done.

We have had the best results with UHT whole milk and organic natural yoghurt from Migros, but others work too.