GLET1031CS0 Washing machinw will not aggitate?

This unit works in all areas except it will not aggitate in any of the three available positions on the timer dial. The timer has been replaced and the electrical print shows an internal switch inside the tub motor for the low speed. Is this switch replaceable? What else could be causing this problem? FYI: I am an electrical engineer and understand this circuitry thoroughly

Thank You