Actually it is bushings not bearings, and in time they get dirty and dry out. I removed my fan, disassembled it, cleaned and lubed the bushings and armature shaft. Scotchbrite works well for that.
Use a non-detergent type oil, such as Zoom Spout (at hardware stores) or 3-1 oil in the blue and white can, not the black.

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John