First let me say that I have been doing a lot of steaming with the Varoma.
My water, in spite of a filtering system, contains a lot of minerals which make it taste good (my own well) but will leave some evidence behind after boiling, especially for prolonged periods.
I generally use distilled white vinegar to clean it but I was all out, forgot to buy it on my last grocery store excursion, and didn't want to drive to the store just for a gallon.
My solution is what I have used to clean crystal vases, and other vessels that develop the opaque crusty formations.
I filled the jug with hot water to above the line of deposits, dropped in two denture cleaning tablets and allowed it to foam and fizz and soak for an hour. Then put the jug on the machine, applied the lid and cup, ran it on Turbo for 30 seconds, then rinsed - twice.
Nice clean jug, lovely clean blades, no effort to speak of.