Hi Natascha,
This is maybe too late but mine was a blown heating element R90 at a spares dealer.
Unplug machine.
Remove the black cover at the back (one screw) and remmove the fan drive belt (elstic)
Remove back cover. mark the 3 wires running to the main machine with numbers on tape on either side of the connector then unscrew the connector block.
near the motor, Remove the big spring holding the main drive belt in tension. Note the place the spring reconects!
Remove the drive belt.
Lift out the stainless stell drum.
Remove the 4 nuts holding the big metal disc with the element (nuts on a circle around the door hole +- 40cm diamter) and lift out the disc with the element, removing the blue & brown element wires.
Put a resistance meter on the old element spade connections
resistance similar to a kettle +- 9 ohms
If the element is broken, there will be no connection between the spade connectors of the element.
Mine was broken inside one of the holding clips, not visable till the element was removed.
Lever the 5 or 6 clips holding the element in place to open up slightly. uncrew the clamp plate near the spade connectors.
Replace the element with a new one if broken.
Reassemble in reverse, starting with the 2 element wires.
Make sure they dont touch any body part when the element metal disc has been reattached.
When reconnecting the main drive belt (non elastic), get somebody to hold in place halfway around the drum, double the end, thread through the tensioner poulley wheel hole and put the loop over the end of the motor shaft.
put the tensioner legs into the 2 slits above the motor.
Reattach the spring.
Turn the drum by hand slowly to get the belt running straight, and help it into place if needed.
Reattach the wires to the cover, checking they are out of the way of the motor pulley when the cover is reattached.
The job takes about 40 mins.
Roger Burdett, May 2008