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

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1984
190e 2.3L
107000 miles