NAD T765 AVR replacement fan?

You could take it apart and try vacuuming first. 

Probably worn bearings. Try flipping it 180°.

Thank you for the prompt and thorough response, imhififan. I ordered a couple of those fans. I looked in the service manuals and note that there are 2 different fans, 330mm and 430mm. I am not sure if this is plug length or what, but I noticed the linked Amazon ones have what appear to be shorter cables. I hope they work/fit!
Sorry I didn’t mention it, but I already tried cleaning. Flipping the fan I would think would defeat the purpose of the adjacent fans as they’re all forcing air in the same direction.
Really cool how supportive this community is - I can’t wait to get back into HiFi now that I have a domicile to support. 

I used to replace the fans in our old CPU's.

If I coudn't find one with the same connector (or needed wire length) without paying a high premium I would just splice the wires from the old fan onto the new unit.

I would solder and wrap them, but a tight twist (or wire nuts) and electrical tape might be OK.

DeKay