I am currently having issues with my 2008 VW Jetta transmission. I am currently trying to diagnose the problem. My shifter has always had a lot of play while in gear since i got the car (with 170k miles). This lead me to believe my shift linkage bushings were going bad, and I never got around to replacing them. Then one day my car became really hard to shift into reverse, as well as more force than i used to have to need to get into 1st and 2nd. 3-5 were unaffected. Now today on my way to work, I shifted into neutral, and the car just refused to go into ANY gear, on or off. The shifter is extremely "tight" and hard to move. Through some messing around to try and find the problem I was able to get the car into 4th gear, with a really good amount of force, and get it to move. it refuses to go into any other gear, almost like the entire longitudinal directions dont even exist. Could the issue be my clutch, something more intricate in my transmission, or my linkage? Any tips or insight would be greatly appreciated.
If it won't go into any gear with the engine off, then I'd say it's almost certainly something in the linkage - problems with the clutch or synchros would go away with the engine not running.
I did once see the same symptoms occur due to a gearbox mount failing however - it caused the box to move just enough to make the linkage bind.
I'd suggest starting with a visual inspection of all the linkages and mounts, see if you can see anything that doesn't look right, or is in an odd position or angle.