Ok, so I let the car sit for a few days and just now when I drove around a bit the speedo worked normally up until around 40mph. Once I got above 40 it would stick somewhere and not go back down until I dropped to below the speed it was stuck at. I got one or two jumps from the needle below 40 when accelerating but the needle always fell smoothly. The odometer is still working properly. I now believe the cable is fine but some of the speedo internals must have some sort of problem. Does anyone know what the inside of the gauge looks like or what the problem might be?