Tried finding a comparable fan with similar specs (size, CFM rating, 2 vs. 3
wire?)
I have a Nidec TA450DC series, and I noticed when I looked at the page for
them, they implied imminent if not already discontinued. I'd look at their page
(it was an easy Google IIRC), and find a close match locally. Nice fan--
heavy metal case, low draw for the rated CFM.
Perhaps you can get some more life from the fan by peeling the label and
oiling there.