speedo needle waving back and forth

[focus09]

thanks Ric for advice hate to say this it didnt help i have replaced cable and added transducer to cable going into trans i am wondering if the cable like you said is not in trans enough i just cannot tell i have replaced speedo altogether and getting same results so i feel it is cable or bad gears it seems steady when travelling when i stop and take off it jumps from 0 to 50 in quick flashes i am lost and frustrated any more would be welcomed and please have a merry christmas and a blessed new year thanks agian