Taurus Fan Test. Need Feedback!

Sounds like something is hitting. Its like a card stuck in the spokes. To me it sounds fast rate, like the blades are clicking across a zip tie. Is it possible that the blade is barely touching some other thing? Those fans are a hurricane. Pretty sure the motor is induction rather than brush based armature. If that is the case, there should be no miscellaneous stuff that could be clicking inside the motor. Since you are committed, take the motor apart and see if a production issue left something less than perfect around the armature. Excellent fan. Nice vid.