This guide provides instruction on replacing the hobbed bolt. The hobbed bolt is a grooved bolt inside the extruder assembly. It's purpose is to grip the filament and feed it into the printer. Over time, the bolt can wear down, which can cause extrusion issues.
Below image shows quality loss with expired hobbed bolt.
1.) Remove the back panel by unscrewing the 4 corner screws.
2.) Remove Extruder assembly by removing 4 corner screws, back these out from inside the build area.
3.)Remove Bowden tube from press to fit connection and the motor plug from the board.
4.)Now you can freely remove assembly from Printer. Push out black c-clip along with the two washers.
5.)Remove 2 silver screws that hold tension on springs.
6.) Back out the 3 black hex bolts.
7.)Twist back and forth to wiggle out the gear.
8.)Push out Hobbed bolt and Replace with new.
Replace~ Make sure Bolt is pushed in all the way with gear.