My 2003 7 speedo has always read 10 mph higher than the car is traveling. After contacting Caerbont,I tried re setting the dip switches to no avail, and after messing about they suggested I replaced the speedo with the latest version so I ordered one. I thought that this would be a relatively painless change, but after fitting it, and trying to calibrate as per the instructions, I tried to calibrate using the Drive to set facility, and although I could access the DTS screen, and select the 00000 option, after driving one mile, the display remained at 00000 and then reverted to set ppu. In addition, although the needle twitches, it did not deflect full scale when switching on while pressing the reset button, and although there is a default set of 008380 the needle does not move when the car is driven. I went back to Caerbont, and they told me that they thought that my speedo was driven from a gearbox mounted speed sender. This is an unusual sender in that it requires a 470 ohms resistor to be fitted from the speedo signal input to ground. They sent me a resistor, and along with some other work I asked Tom New he could fit the speedo for me. After wiring in the resistor, ~Tom has has had about as much luck as I did. Before i give up and send the new unit back, is there anyone who has done this or is able to offer any suggestions. Many thanks