Sympthom was with us that the hobs an eternity needed to heat or to heat water. To blame was the regulator.
The supply of spare parts the country, incidentally, was first class and super fast!
Thank You!
Update 01/16/2015
Unfortunately, the governor has given up the ghost - ie the heating circuit 2 is randomly switched on or off on the big Ceranfeldplatte. Does not matter - comes just a new switch back inside.
