TSB #131 - January 16, 1970
(1970 Ford and Thunderbird)
A binding speed control sensor may cause speedometer noise and/or the pointer to waver. Remove the speedometer cables from sensor and check sensor for a binding shaft.
If sensor is binding, replace sensor and inspect the lower cable core for damage. Before torquing cable nuts to 18-25 inch lbs. ensure that the washer is seated in the unit.