Hi. I have a G7856 Miele professional. Occasionally it halts with an error of F1E. Several days ago I inspected the heater level switch and tested it. It made a snapping noise one time and then after that it indicated open and closed as it should. I washed several loads, pass.It failed again, backed the level switch screw out 1 turn. Washed one load, pass. Now, it fails after the rinse and before the dry cycle, same error. I think the level sensor is faulty. What are your thoughts? Also, I tested both the hot and cold lines for water flow by energizing the solenoids. Thanks