Quick update. Blowing out the fan with compressed air solved my fan noise issue. The issue has not returned, though we have new carpets in the house which makes for cleaner house.
As far as I can see no damage to the fins, sealing tape or fan was done.
CPU has been run hard at times. 32 gig memory and two internal SSD drives.
Parts: Used an air compressor at 30 psi and 1/4 inch air hose with lever style blow gun. Light source to see the cooling fins helps.
Alternate parts: can of compressed air used in a well ventilated space.
Action: open the case, direct air toward the fan inlet
Technique: Double check the output air flow is 30 psi. Slowly depress the lever a few times to get the loose ($# &^), er stuff and dust out. Then reverse the fan's spin by blowing air on the other side.
Add more air pressure being careful not to bend anything like the cooling fin blades. May try blowing air *into * the NUC and then go back to the fan.
Legal: Use at your own risk. I am an armature acting in good faith at the limits of my experience. Ain't my fault, Ain't Itnel's fault if something breaks. No warranty given nor implied.
That said. NUC seems sturdy. Be careful. Enjoy