I need 32 spoke wheels for my weight. The OEM are 32 as well. The Craigslist wheels are 11-speed hubs and wouldn't work on a 9-speed drivetrain. I think this Park Tool instruction was what the mechanic was saying. "Hubs using cartridge type bearings are not serviceable in the sense that they can be dismantled and adjusted. As cartridge bearings wear and develop play, the entire cartridge unit is replaced. Cartridge hub service is not covered in this article." This is why they said replacements aren't available.