After sensing/soak phase, a switch sounds like water is about to turn on and start spraying, but then suddenly dishwasher turns off. I have pushed stop subsequently, and the display shows "2" (minutes) and I hear water draining into the disposal. I have read some other responses, and think it may be the screen/chopper. I have well water and have checked the valves, removed the intake water line, lower spray arm, soil accumulator, foreign body protector and screw from the inlet protector, but it seems to be stuck and will not lift out. Suggestions for loosening this part? Thank you.