If it is a Gentle Annie then it is a lot more than 10 years old. The last one of these where made about 22 years ago. The agitator is held in by the inside fins that you can see when you look down the inside tube. A special tool is needed to move the fins sideways enough to release the agitator. Where about are you? Is there a service company close by who may have the tool needed?
Linoln Appliance NZ
May 2013