I have an XP4 and have had a XP3 in the past but since my last clean my XP4 isn't working. I called the help desk and they told me to check if the impeller was turning and the white blades definitely are when I plug it in but the plastic blue circle piece the sits on top of it doesn't turn. Is it supposed to? I have a sick turtle and he needs the filter bad! When I prime it and push the lever down the filter fills with water but when I plug it in it just doesn't pump it. Any help or suggestions would be very helpful!!