Alternator whine

[AV8R4AA]

I have a 2004 air cooled alternator that has a slight whine.
It's not loud, just an intermittent whine.
Bought a mechanic stethoscope to isolate the noise.
It's the alternator for sure. Twice I have removed the serpentine belt
and spun every bearing pully. The last time I removed every pully and regreased them, they are not the noise. Even the alternator spins dead quiet.
Which is odd, because every alternator that had a marginal bearing, sounded
bad with a spin. Mine is solid and smooth with no noise by hand.

It's not a full time alternator whine, I think it's just one of the 2 bearings.
I hate to have to buy a 300+ new alternator for just one bearing.
Anyone have this issue?
Any new bearing kits to install?