Located on underside of pivot joint on handle between the pivot nut and the handle.
Not to be confused with a "Tension Spring".
Bigsby Vibrato Handle Pivot Spring. Diameter is 0.37 in. Height is 0.359 in. Used for handle pivot resistance. Located on underside of pivot joint on handle between the pivot nut and the handle. Not to be confused with a "Tension Spring". Picture is enlarged to show detail. Bigsby Part# 0495-1960