Hi
Are you talking about the electric fan(s) in front of the radiator, or the one on the water pump.
For info the electric one(s) are there primarily for the AC, but will cut in for engine cooling in extreme cicumstances. Cars without AC do not have the electric fan(s) at all.
If its the water pump fan you will need to replace the viscous coupling these are not to expensive new from MB, the electric item(s) can be sourced quite easily and inexpensively second hand but make sure the pt. No. matches, having one go on my C43 the fan motors are not designed to come apart for bearing replacement, though that's not to say you could,nt do it but you would have to take the bearing to a supplier to match up and hope its available.