I have inspected the belt and there are no signs of damage. Evidently the noise is caused by the slow wear of the toothed surface, and subsequently the belt dust being deposited on the pulleys. Although the belt is still serviceable it makes this noise. Evidently the dealerships routinely greased the belts at service to increase their life (at least they did here in the UK). Ultimately I will replace it, but was just trying to buy some time and avoid unnecessary cost
