Whirlpool washer GSQ9340EQ0: Stop and go

Model Number: GSQ9340EQ0 Brand: Whirlpool Whirlpool washer GSQ9340EQ0: Stop and go - Works for 10 seconds and then nothing for 10 minutes, repeat... My Whirlpool washer (Model GSQ9340EQ0) is having the following problem. On starting the wash cycle, it fills up fine. Then it starts agitating. It agitates for about 15 seconds and then stops for 10 minutes or so. This pattern repeats itself for hours - through the wash cycle, through the rinse cycle and then through the spin cycle. Between the short periods of activity, there is complete silence. During the periods of activity all sounds are normal. And finally the wash cycle is completed after 7 hours or so. Any help on where to start to troubleshoot? TIA!