I am looking at purchasing an older Montero 4 wheel drive.the owner states that the previous owner tried to engage the 4 wheel drive while in high gear in motion.Then what happened as he has stated is that the transfer case through a safety mechanism or "Switch" to inhibit the engagement.And that all that needs to be done is to disengage the mechanism to fully restore the 4 wheel drive.Is this correct? If so how and what is the easiest way to do this?