I do almost all of my own maintenance on the family's bikes, but I've run in to a bit of a problem. I have some Older Mavic Cosmic wheels (back before they were Carbon) on my daughter's bike (I bought them used). The Mavic hubs seem to have a propriety hub system and apparently a bearing cartridge.I can hear the movement of the bearings when the wheel spins (or even when she rides it). Oddly enough, the wheel still spins pretty freely.

If anyone has any tips on servicing these, I'd appreciate it.