Abstract: An extruder has an intake barrel, a degassing drum connected to, downstream from, and coaxial with the intake barrel, and an output barrel connected to, downstream from, and coaxial with the intake barrel and degassing drum. A driven shaft extends through the drum and barrels and is rotated for forming a plastic melt and advancing the melt through the intake barrel, degassing drum, and output barrel. A plurality of degassing screws surround the driven shaft in the degassing drum. A screw guide rotationally fixed to the shaft has respective seats for the degassing screws. Respective drive gears rotationally fixed but removably mounted on the degassing screws are received in respective seats in a gear guide separate from the screw guide and rotationally fixed to the shaft. A ring gear is rotationally fixed but removably mounted in the degassing drum and meshes with the drive gears.