Start with the rods and the levers' position, as this may be the source of your problem. It is very important to lock the three shifter levers with a pin, or a long M6 bolt. All three levers have a hole to that effect that align with two holes on the shifter body on each side of the levers. Do this from underneath the car, as obviously the length of the rods will be different if you pull the shifter to do this from the top. Then see if the rods slide freely in and out of the lever bushings whith no gear engaged.