WD-40 is NOT a lubricant. It will actually wash the lubricant away. The fan motor will either have preoiled bronze bearings or sealed bearings.
It could be the thrust bearing is bad on the motor and allowing the fan to contact the housing.
Amateur Radio Operator (KE5DFR)|Full-Time! - 2012 6.7L Ford Crew Cab Dually -2013 HitchHiker Champagne 38RLRSB - Travel with one Standard Schnauzer and one small Timneh African Gray Parrot, retired mechanical engineer