the brushes do not rotate in my dyson 07 model?

The brush at the front of the dyson do not rotate. I have replaced a new motor (due to the other one being burnt out). I have stripped and cleaned everything and examined the belts etc (including clutch belt). Both belts appear to be fitted correctly but when manually turning the motor spindle the front brushes still do not appear to move. Please help. (could it be possible that new belts are needed?

pete shields
July 2007