Speedometer cable shakey below 50MPH

[ps2cho]

On my 88 300TE the speedometer will wobble and shake at anything under 50MPH at which it will stop and act normal over it.

Since I am pulling the transmission to do the front seal in the next couple weeks, I figure this is a good time to resolve this.

Is it time for a new cable or could it be something simpler than this?

Thanks,