Speedometer Inaccurate and Bounces

[kdml]

The speedo on my '83 is not accurate and it bounces at lower speeds (below 20). I lubed the cable, but it still bounces. I was thinking of replacing the speedo to see if it will correct both issues.

I was also thinking that the gear on the end of the speedometer cable might be wrong and causing the inaccurate readings, however, the amount by which the speedo is inaccurate changes based on my speed. For example, at 25 the speedo reads 4 mph too slow, but at 55 it reads 10mph too slow. Would this be an issue with the cable/gear of is there a problem with the speedo itself?

Thanks
Doug