All of a sudden one day I am getting this squeaking noise coming from the gearbox/gear stick of my 1988 Mercedes 300TE.

If I hold the gear and move it slightly, the noise either stops or is suppressed.
It is not a grinding noise and is affected by road surface, not engine speed. I can physically feel the stick thumping and vibrating over bad surfaces. It squeaks constantly all the time.

Any ideas what it could be?

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