For any one with this problem. I had this to and took pump assemply apart and fixed everything. The hum is because the little plastic fin wheel came off the motor shaft. It is just pressed on. I repressed it on and it worked for an aditional month. It stoped working again and i had to buy a new pump motor. (about $48). You can do it your self if you do not want to pay a repair man. You can access from the bottom. It is located underness right behind the drain filter. When you look into drain filter opening in front it is the opening on the left hand side. You shoult be able to see the plastic paddle wheel. The right hand sid is the cerc pump. Takes about 1/2 hour to disconnect and reconnect new one.