The Gearbox is a Volkswagon MQ200 series installed on a Skoda Octavia 2008. I experienced problem with the reverse and 5th gear engagement, so attempted to fix the problem.
While tightening the nut/bolt (marked in red circle) to tightly connect the "Gear shift lever" on the "selector shaft", the nut/bolt has broken off or snapped. I am not sure whether the snapped part is a nut or a bolt. If it is a bolt then it should be possible to extract the broken bolt with a bolt extractor.
But based on the following picture, it seems, what is broken/snapped is a nut together with the extended portion of the bolt as marked in the blue circle in the bottom picture.
Do I need to change the whole gearbox due to this broken nut or bolt? Somebody suggested trying to fix the connection by welding. Would this be a good idea?