Washer has developed an intermittent problem where it does not agitate. Timer is turning and fill, drain and spin work fine. If I start at the beginning of the cycle it will fill do nothing while timer runs through the wash cycle and then when the timer reaches the Darin it will drain, spin and fill for rinse. Again it does nothing until tit reaches drain and spin. Sometimes it works just fine through the whole cycle. Sometime it starts to agitate halfway through the was cycle. Any thoughts on what it may be.