Every time now the fan sounds I think it is the fan dut not that sure it sounds as if metal is hitting metal can anyone help me with a cause for this

Pat walls, October 2015

If it has a round element around the fan the element may of overheated and bent out of shape and now the fan is hitting it. Take the cover off the fan and look.

Lincoln Appliance NZ, October 2015

Yes - the fan blades are just soft aluminium - with the passage of time constant heating and cooling have caused one of the blades to bend very slightly. The bent blade is now striking something it previously missed.

You might consider removing the plate that covers the fan and adjusting things.

As long as the fan rotates there should be no real harm.

Good Luck..., October 2015