Annoying Speedometer Noise at Cluster

It's probably not the cable at all but the speedometer has dried out. My dad has a spring loaded tool that screws onto the back of the speedometer that he has used for decades when he had his own garage. You fill the reservoir with 3-in-one oil, release the spring loaded plunger and it pushes the oil into the back of the speedometer. Been using it since the 60s to stop the kind of noise you describe and to stop the binding that causes the needle to bounce around. It works great! And, you can do it without taking the dash apart.

Careful, WD-40 will dissolve and dilute what lubricant is already in there.