Use these four parts to assemble the Spring-loaded Drive Block alternative to your MakerBot Replicator 2 extruder. The design files and assembly instructions for this system are available on the MakerBot Thingiverse page. Print the available parts and attach them as instructed. Check out our installation video for more information. The Spring-loaded Drive Block is a simple system for pressing the filament against the drive gear using a constant amount of force. We salute the innovative Thingiverse users who worked collaboratively on this design over time!