our tiger shark stopped moving. When first put on it will work for about 2 minutes then it stops moving, it still has good suction, just won't moved. Tried shutting it off, unplugging for 10 seconds and restarting, but the same thing happens. We read on a web page there may be water inside the motor, so we took it apart, but it was dry. Now we're having problems putting it back together. The gasket seems to large now. Does anyone have instructions for reassembling the motor?