First step, do you have to press down on the stick to select reverse or does it just slip across the lockout gate? If so you'll need the gearstick housing repair kit from VW, its pretty straightforward to do but a bit fiddly, part number is 191 798 116A. I would recommend you get the genuine kit, this isn't a job you want to be doing twice!.
1. Remove the gearstick gaitor & centre console to give you more room to work
2. Undo the 2 10mm nuts either side of the gearstick.
Now get under the car
3. Remove the exhaust centre heat shield by removing the 6 nuts/clips holding it on, then rotate it round the exhaust an off the car
4. Shove the housing up into the car, it is only held in by gravity & grease at this point
5. Remove 4 13mm nuts holding the plate
6. Now get back in the car, pull up on the stick and push down on the plate you have just undone
7. Next Jiggle the housing about untill you can get it out
8. If the ball looks like it is worn you can remove it, I didn't bother as it looked OK. Its tricky, you need to press the ball upwards while someone holds the gearlever down, then you need to remove the split pin. Not an easy task!
9. Refitting is the reverse of removal
If it still requires a good shove to get into reverse its probably the linkage bushes/alignment. Start by getting a linkage bush repair kit from GSF, then have a fiddle with the alignment if its still dodgy.
