Speedo "stuck"

If the speedo head magnetic drive parts contact each other and seize up it trashes the cable.
Twists it all to hell. :D

When you get the unit out of the cluster look at the back where the cable normally attaches and notice the little clock spring lookin assembly.
It's the calibration adjustment.
Betcha it's not attached to the body of the unit any longer and is not retuning the needle to zero.
The last one I fixed like that I estimated where it looked like it might have been and epoxied the spring unit back and got it within 5 mph. :D

Oh, and it's totally acceptable to hold the drum the needle is attached to and lightly twist the needle if it needs moved, removed or adjusted.
It's just lightly pressed into the drive unit.