Now bear with me as I am new to this 4x4 malarky...
The locking hubs, are you supposed to be able to turn them from "Free" to "Lock" by hand? Mine are particularly stiff, and won't budge by hand. Is there a tool or something you're supposed to use, or is it a case of getting a pair of pliers on them??
Please excuse any double-entendres in the above question!