Saeco Magic de luxe breaks off during grinding

Hello,

maybe someone can help me. I have a Saeco Magic de luxe which sometimes breaks off during grinding. It usually doesn't eject the coffee at all, but grinds the coffee by pressing the button again and then continues to press the coffee until it is in the cup.
Sometimes the machine runs normally and sometimes it just breaks off. More often it breaks off during grinding if the button is pressed twice (i.e. for 2 coffees in a row). Then it also happens that the 1st grind is ejected dry, then it breaks off (the rest of the 2nd grind remains in the grinder) and only continues grinding the next time the button is pressed.

HAbe the MAschine already clean cleaned, partially disassembled and cleaned but as it seems to me, is something defective! i

would be very grateful if someone can help me to find out which part is defective here.

thank you