The GE washer timer knob is the part that turn on and off the timer. It is also the part that turn the timer internal gears and contacts on the desired position inside of the timer.
 

The timer shaft has some gear cuts molded on it. The GE washer timer knob has similar gear cuts on it too. When you push the knob, the gear cuts on the knob mate with the gear cuts on the timer shaft and when you turn the knob clockwise, you will turn the timer dial on the cycle you desire.
 

The main reason that the gear cuts on the timer knob wear out is because the user don't push the timer knob far enough when is turning the timer dial.
 

The GE washer timer knob is held in place with a plastic piece that hooks on the timer shaft groves.
 

To replace the timer knob, you will need to use a needle nose pliers to pull out the knob retainer, then the knob will  come right out.
 

Take the new timer knob insert the retainer on the groves of the knob and push it on the timer shaft until it snaps on place.
 

We hope that his GE washer timer knob page be of help to you.