Time Traveller

Greetings,
I bought my 190E 2.6 last October, when the long Wisconsin winter was already starting. Now, after several false starts, the weather is finally starting to warm up, and my electric auxiliary fans have been running for the first time. But...
The other day, as the car was idling in the parking lot for a little while, I noticed a fast-paced rhythmic squeaky noise. I lifted the hood and determined it was one of the two aux fans... the other was not spinning. I gave the dead one a nudge on the smooth hub with a handy tool, and it took off, albeit slowly. When the thermostat cooled enough, the shut off again, and I watched the cycle one more time. Again, the first fan squawked and the second one needed a push.
After shutting the car off, the squeaker spins freely by hand, but the nudge one seems to have some smooth, even resistance.

Is there a way to clean/recondition these? do they require outright replacement? Thanks!