Unplug the washer from the power outlet.
Grasp the front of the knob that isn't turning. Slip the tip of a screwdriver behind the knob to release the holding clip.
Pull the knob straight off the washer.
Inspect the back of the center of the washer knob. If the small plastic teeth in the center opening are worn replace with a new GE washer knob. If the teeth look OK proceed to Step 5.
Inspect the teeth on the small plastic piece that the knob was connected to on the control panel. If the teeth appear worn you will need to replace the timer mechanism itself. If the knob did not turn or spin at all and the teeth of the plastic piece attached to the timer appear fine the timer mechanism may be broken.
Remove the screws on top of the control panel. Pull the panel forward. Disconnect and remove the timer with the bad teeth or with the problem of not turning at all.
Connect a new timer that matches your particular GE model. Replace the control panel and push the new knob in place. Make sure the knob's main arrow is lined up with the "Off" setting.