GE washer WNSB9080B only allows me to run "Drain and Spin", no other cycle. It wounds like there is still water inside when I move the drum around.

In top loading washing machines, the agitator is responsible for moving the clothes through the water and detergent and is driven by the output shaft of the transmission. The output shaft is normally splined and the center of the plastic agitator will have a matching spline to ensure a tight fit. Depending on the brand of washing machine, the agitator may be a single piece unit or a two piece dual action agitator. If the single piece agitator or the lower portion of a dual agitator does not oscillate back and forth during the wash cycle, or if the agitator can be turned on the transmission shaft, then the spline may be damaged and the agitator may need to be replaced. Most agitators are held in place with a bolt that threads into the top of the transmission shaft and is located below the softener dispenser or top cover. Some models use a small set screw in the barrel of the agitator just above the base to secure the agitator to the shaft, while some will use a rubber o-ring to provide a tight fit. When the retaining device is removed you should be able to lift the agitator from the shaft.