Ticking Speedometer...Not working?

My speedometer is making a ticking noise while up to speed and the numbers are just jumping back and forth it worked fine, anyone know whats up.

could be a failed cable

I've had the same problem too; replaced the speedometer cable, and the problem remained. I even replaced the speedometer with the same result. Perhaps it's the speedometer gear near the front wheel? Makes a buzzing noise, can be very loud.