hi what,s involved changing the speedo drive in the auto gearbox, i can not get my speedo working, i have changed the speedo gear, but that do not seem to pick up any drive from the drivegear, i have felt the gear with my finger but can really see anything. the speedo cable is new, so the fault is in the box.i did notice a washer in a drawing between the cable and the box , does this need to be there?. paul