Possible Causes:
The bag suspender is worn or not properly functioning. See DELTA Service Procedure 006.
The level sensor is not detecting solution. See DELTA Service Procedure 007 for Analog Level Sensor.
The motor stopped turning. Check the packing nut to make sure it is not over tightened. See DELTA Service Procedure 001.
The motor needs to be replaced. See DELTA Service Procedure 023.