As Mat says, you will only know when the box is off unfortunately, but if it has more than 2 teeth's worth of play then it's time to replace. My mates was about fooked when he checked his and like a lot of people couldn't really have the car in bits and then have to wait for a new flywheel to be delivered, so ordered both before hand.. His had about 20k on it too, but that doesn't mean your's will necessarily be fooked.. Just that it may..
![Walking Sad :sad1:](https://www.mk5golfgti.co.uk/forum/Smileys/newsmileys/sad1.gif)
His was slipping in most gears, but not ALL the time.
Not really what you want to be hearing I know mate, but going off other people having similar issues, it may cost you a bit more than you had hoped..
![Walking Sad :sad1:](https://www.mk5golfgti.co.uk/forum/Smileys/newsmileys/sad1.gif)