My W124 speedo needle bounces a little at low (< 30 mph) speeds...did so when I bought it at around 72K miles. Never bothered it, and it hasn't gotten any worse.

But with my VW, I found that the culprit was always a bent or kinked cable...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car