Any help appreciated

[DuncanG]

I have just bought a 2002 Passat Estate 1.9 TDI on a 52 plate. Private sale!
Having had it for 48 hours I noticed the rear wash wipe jet wasnt working..it was blocked. Sadly I had been trying to use it whilst it was blocked and appear to have burst the feeder pipe inside the trim on the rear tailgate. Screen wash was dripping out around the bottom of the trim on the inside of the tailgate. This seems to have had the knock on effect of causing problems with whatever sensor is fitted to tell the car the tailgate is closed which has developed an intermittent fault indicating the tailgate is not closed when driving along(loud audible warning)This in turn is causing the alarm to go off when the car is parked and locked. I cant work out how to get at the interior of the tailgate(cant get the trim off) and I cant work out where the sensor is that registers if the door is open or closed. Can anyone tell me a) How to get the trim off the inside of the tailgate without breaking it all and b)Where the door closed sensor is.

Thanks in advance