Since I have owned my FTO the plus and minus on the shifter have been missing, well not so much missing but they have actually fallen into the hole and are caught in behind.
What has to be taken off in order to get at the shifter? and what has to be taken off the shifter in order to get the plus and minus?
Take the shifter knob off.
Take the rubber ring around the shifter off.
Carefully lift the surround up from the bottom.
There are 4 screws holding the plastic thing with the + and - symbols on it, and your done.
You might need to move the shifter into gear to give you more room to move things around.