I've got a Kenmore 587.15173400 dishwasher. We noticed the bottom arm sprayed well but the top arm wasn't rotating or spraying since insufficient water was being pumped up there to power it. I changed out the pump but it made no difference. I discovered by accident that if I opened and closed the door quickly while it was washing that suddenly the pump pressure would increase dramatically and the top arm would get plenty of pressure. So, it appears the pump has more than one speed, which I didn’t know. My question is why would opening and closing the door quickly cause the pump to increase and why isn’t it running at this higher pressure when washing as it obviously should be?