My simpson esprit 450 is not pumping out water, help?

My simpson esprit 450(36p450 j*02) was making strange noises then stopped pumping out water. After inspection of the pump I saw that the rotor was not spinning. I assume this means the pump is broken but am not sure if it means the filter is blocked and this in turn stops the pump rotor from spinning automatically. I can't actually see a filter on this model and don' have a schematic to check. I don't want to spend $70 on a pump if it's not the prob. Any advice would be appreciated thanks