Speedometer flutters below 10MPH

[gcw206]

1969 280SE W111 Coupe, with an automatic transmission.
My OE speedometer fluttered an acceptable amount below 10MPH.
Then I damaged the OE cable while assembling the dash.
The OE cable was replaced with a non OE cable.
Then it skipped a lot, and the new after market cable was replaced with another by the same vendor.
All worked pretty well for a while.
Now my speedometer flutters a lot below 10MPH.  (Got worse over past year or so.)
It is either the gears in the automatic transmission; the cable; or the head unit in the dash.
I have found an OE MBZ NOS cable, but am I looking in the right place?
Thanks, Galen

[kampala]

There is a lot written about this issue on this site.  Try the search “bouncing speedo”

Or similar terms to bouncing.  You should find a lot of info. 

[ja17]

Try loosening it up a bit at one or the other end.

[gcw206]

I removed the speedometer head and cable;
Took to bench, hooked up cable to a variable speed drill;
Speedometer still jumped at low speeds;
Decided that transmission sending unit was not the issue;
I bought a NOS MBZ OE speedometer cable;
Installed, and problem solved.