I have aquired a loose spoke and a wonky rear wheel on my recent tour. The rear wheel wobbles when I spin it and rubs against the brake blocks (which i have had to loosen off to let the wheel run freely). I tried to tighten up the spoke but it just keeps popping out again at the central hub end. Is this a job for LBS man or is there anything i can do myself to fix this? I think the technical term is that my rear wheel needs 'trueing'.