Most likely it's the shift actuator but this washer design has had many problems. I would first unplug/replug all the wiring connectors. Tilt machine back for access to connectors for motor, capacitor, shift actuator and pump. You might want to pull the pump and make sure nothing is caught in there. Also do the connectors at the control board. Check for error codes as per tech manual and reset them. Perform the calibrate function. If nothing works, replace the shift actuator
. It is a very high failure item on this washer design. If you buy it from here and it doesn't solve the problem, you can return it.