A servo valve for an actuator is described. The servo valve comprises a housing and a sleeve provided within the housing having a plurality of metering holes for communication with a cavity within. The servo valve further comprising a metering rod provided with metering members on a central rod for metering flow into and out of the cavity through the metering holes. The metering members comprise annular elements which are located axially on the central rod by an interference fit. The position of the metering members can be adjusted through using heat to thermally expand the metering member relative to the central rod to release the hold of the friction fit, allowing the metering member to be repositioned by being slid along the central rod.