The digital trip on my 2003 07A has started to play games. The Clock works ok and the speedometer is fine. The digital trips work ok upto about 35 mph, then stops recording. When the speed drops it starts working again. I have checked all the plugs and sockets and opened up the trip meter and speedo assemblies to see if there is anything obviously wrong and it all looks like new. I suspect the pickup unit in the speedo but am stuck as to what to do next. Any ideas would be much appreciated.