I have a noisy pentair WFE 28 and was hoping to replace the motor. When I tried to disassemble one of the 4 long bolts snapped. There was a lot of corrosion on other bolts. It's a 7 year old 30k inground A & S gunite pool. Looks like I need to replace pump. Seven years seems pretty good life span for NJ's weather. Recommend using same pump $600 or is there a better pump for the money? Looks like the Pentair whisprflo has many versions w/ similar model #s as well. Full rated, uprated...was the dif besides cost?