Speedo issues

[changedbychrist]

I have a 1990 240SX that displays the miles per hour accurately for a few miles after the car has been setting. However, within about five to ten miles, the needle starts bouncing and then "pins" at either the left or right end. It may come back to position temporarily, but it never holds. I pulled the mechanical module out of the transmission today, and both gears look fine, the bolt was tight, and everything appeared to be fine. Is it possible that somethings messed up at the dial? I noticed that the sending unit utilizes an electronic wire rather than a hard cable. Would there be some sort of malfunction along the way to the dash?

[NISTECH]

its likely the speedometer head itself thats the problem.