Hi Alan
once again thankyou for your help. I've managed to replace the
impeller and the water is getting up to the powerhead but the overheat
alarm is still going off. As long as i keep moving at a steady pace
its fine but as soon as i stop the alarm sounds. The impeller was a
very tight fit, is that normal? Could it take a little while for the
impeller to wear in?

cheers

Dave