The indicator uses an operating element at a given radial distance from the shaft longitudinal axis and at least one cooperating sensor (46) supported by a holder (45) for adjustment along the circular path of movement of the operating element, via a guide (44) provided by a sensor support (36). The precise positioning of the sensor is effected via a setting cog (66) supported by the holder, engaging teeth extending around the guide, so that the sensor is moved in a circular path by rotation of the setting cog.
