An extruder has a valve assembly configured to move pins to open and close the nozzles in a multi-nozzle extruder head independently. The pins of the valve assembly that are driven by actuators into and out of engagement with nozzles in the extruder head are positioned within sleeves that extend between the valve assembly and the extruder head. A gap is provided between the extruder head and the end of the sleeves proximate the extruder head to enable thermoplastic material leaking from the extruder that contacts the pins to remain in a melted or plastic state so the thermoplastic material does not interfere with the movement of the pins.