it's fairly easy to push the instument cluster out from behind. unscrew the speedo drive to make sure it still spins. it might be the cable.

(if you remove the cluster, don't start the car. you will be covered in oil.)

if the cable spins, your problem is in the speedometer itself.

on some older mechanical vdo's, the 10ths wheel gets stripped from the shaft. if you are confident, you can dismember the speedometer and force fit the 10ths wheel back on with piece of waxed thread ( had worked three times in three different cars )

do not reset the trip meter while moving. that is what strips it from the shaft.

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