Our washer is 12 years old, been working like a dream until this afternoon. Have done a couple of loads today, and on the last load, it filled with water, then would not agitate, spin, or drain. So, I have a load of clothes sitting in a tub of water. It makes a humming/buzzing noise right around the control knob when in the agitate, rinse, or spin cycles. If left to continue humming, a slight burning odor emits from the tub. Any advice is greatly appreciated!!