A nozzle has a valve pin for controlling flow of molding material through a nozzle melt passage. An actuator has a stationary part and a movable part. The actuator further has an extending rod connected to the movable part thereof and a block connected to the rod, the block being movable with the moveable part of the actuator. A pivoting linkage element is rotatably connected to the block of the actuator and is connected to the valve pin of the nozzle. The pivoting linkage element moves the valve pin in response to movement of the movable part of the actuator. A bracket is connected to the stationary part of the actuator. Two sensors are connected to the bracket for detecting different positions of the block. The sensors may be air proximity sensors.