Do you know if you have the vacuum operated hubs in the front? Can you see two hoses coming out from under the front guards towards the back of the wheel hub? (one brake line + one other going to the center of the hub)

If you do see them, then the best solution is to get some manual "Warn" hubs (part number #60247) and fit them (straightforward, about 20 mins with a 10mm socket).

The vacuum hubs are notorious for failing more often than Paris Hilton has been partying (and with similar disastrous results...).

The whole design setup is at fault, and despite 2 factory redesigns of the seals, they still leak, leading to debris and goop being sucked into the hub mechanism and causing similar issues to what you describe. There is no satisfactry fix for the vacuum hubs.