Speedo problem , changed cable , trans gear and gauge

I'm pretty sure , but I'll check it out again . Tested my old gauge with new cable and a drill , it still jumps around like crazy , so it's a good thing I replaced it .
Will try re seating the cable , play around with it , hope it helps , I really don't like the needle jumping , even if only for the first 5-10 mph .
Maybe I'm a bit to anal for a classic car ? Funny cause on my new cars I really don't give a damn about things like this .