Found this today in a 2005 Beetle with the 6 speed automatic. Vehicle would be fine at first, but after driving a bit, all the gear indicator letters on the dash would have brackets around them. I was about to replace the shifter assembly (which is where the tiptronic switch is located) and found this.
The area you see in the lower part of the picture above is the tiptronic switch. You have to remove the printed circut board and the plastic cover that is directly below it. See picture below.
The image below shows the two magnets that trigger the tiptronic signal. The one circled was found down on tunnel behind the shifter assembly. Since it is a magnet, it didn't go far. It just snaps into place, but I used a dab of a good glue to keep it in place. After 50 miles, it works like a champ. I have see a writeup for this on older Passat's but no pictures were posted.