My aux cooling fan bearings are starting to make a loud noise when the fan is engaged.

-Is there any way to lube / replace the bearings or do I need to replace the entire aux fan unit?

-If aux fan replacement is required, could someone give me some guidance on how to remove and replace- I have the W124 service CD and can't find any reference to this topic.

I did a search earlier, but nothing in the archives really gives any DIY guidance on replacing the fan or quieting the bearing noise.

Thanks!