you might try lubing the speedo cable, and check for crushed places on the outer housing, make sure no tight bends, if that doesnt do it you will have to get the speedo head out of the housing, on top where the speedo cable screws on to the speedo you will see a small welch plug, it looks like a small freeze plug, remove it with a machine screw that fits snug in the cap, under neath it you will find a felt wick, remove it, now put 3 or 4 drops of 3n1oil in the hole, turn speedo shaft with your finger till it turns free, clean felt plug with gas paint thinner or what ever, dry and put some of the oil on it, put in hole and add a few more drops of the oil, replace cap, add a small amout of oil on all moving parts you can reach, dont over do it, now your ready to install speedo and take a ride and see if that helped, this wont work on an electric speedo