My Kenmore Series 80 washer recently overflowed. When I pull out the dial to begin the cycle, it fills and fills and will overflow without beginning to agitate. When I turn the dial past fill to the point between wash and rinse, it will agitate for a few minutes before continuing to spin out and begin to refill for rinsing...at which time it will overflow again. Is there some sensor that detects the water level setting and causes agitation to begin? Can this sensor be faulty? And how can I replace it?