Go to store....
Buy new lighter...
Get back to truck...
Open package....
Using a forward pushing motion, insert new lighter in old lighters socket.
Am I missing something? It is very easy to do, why are you asking?
If you lighter is broken, there isn't much to go wrong, fuse (you said its OK), or the lighter itself. The plug is basically a wire and metal housing. Nothing to go wrong there, the fuse would go if the wires shorted out. I have had lighters seem to not work because the inside of the plug was so full of ash and tobacco, needed a good cleaning out, just cause it wasn't making good contact with the electrical contacts. I have also had the actualy lighter go bad from over use, see instructions above for fixing.