A speedometer shop told me that if my speed indicator needle swung widely at slow speeds, it was the cable. If it was smooth at slow but varied wildly at high speeds, the speedometer needed lubrication. Mine did both. I removed it and also removed the back. Upon inspection, I found a tiny hole coming up from the bottom and applied some 3 in one oil. It all of a sudden spun easily by hand. I cleaned the worm gear that drives the odometer as best as I could and lubed it with some grease. I put it all back together and test drove it up to 70 mph. It still jerked at slow speeds but was as smooth as silk at high speeds. I now believe that my speedometer is good (now lubricated) and that all that I need to replace is the cable.
John
