The 3 most common part(s) or condition(s) which cause the symptom Washer won't agitate are listed below starting with the most likely. Check or test each item and watch any available videos.
RepairClinic Item # 1094190
If the washer won't agitate the lid switch assembly might be defective. This is a very common problem. The lid switch assembly can fail either mechanically or electrically. Test any electrical switches with an Ohm meter for continuity. The switches should have continuity according to their design.
RepairClinic Item # 1185395
If the washer won't agitate the drive belt might have worn out. Over time the drive belt will fail just from normal use . Replace the belt every two or three years depending on how much the washer is used.
RepairClinic Item # 1185421
If the washer won't agitate the drive motor might be defective. This is not common. Check all of the other related parts to this symptom before replacing the motor. If the motor is visibly burned out or physically damaged it will have to be replaced.