Bouncy Speedometer Needle
 

I have a 90 300E.

Can anyone tell me why most of the time the speedometer needle bounces up and down around the speed I am driving? Other times (far fewer) it is dead solid, right on the money.

Any suggestion would be appreciated...
Thanks
Steve

My needle does that too on my '84 190e. prior to me having removed the cluster to fix the instrument lights that wouldnt turn on after I replaced the cluster the bouncy needle affliction occurred. it turned out that the traces on the circuit board had somehow burned out on the backside of the clusters circuit board. I was able to fix it with some small guage insutaled wiring and very careful soldering