At last I was able to convince them that my weight is moved over a longer period in the range of 2 kg.Therefore me at a 4-week rehabilitation stay. And does not differ by 20kg, wants as Curling these so-called "balance" white. Maybe yes, a random generator is installed, the auslost the "weight".
Since repair (see other comments) probably does not make sense, the unit now flies on the garbage.
My verdict: Stay away.