If you hear a ticking/clicking sound, it is probably the cable. Pull the cable out of the casing, clean it and grease it as has been suggested. Look for worn spots or broken wires in the cable. Worn spots may indicate a kink in the casing, in which case you may need to replace the casing- but not necessaily, if you can straighten it. The cable itself can be replaced separately from the casing.
If the noise you hear is intermittent buzzing or squealing, the head needs to be repaired. Speedometer shops can handle that for you.
Harvester
