Replicator 2 Extruder Upgrade with Adjustable Spring Tension

This is a modification of the Replicator 2 Extruder Upgrade by whpthomas, in order to adjust the spring tension as needed. This is probably most beneficial for people who have a hard time finding the right spring for the original design.

The arm has been modified with a hole for an M4 screw, and cutouts underneath to fit the corresponding nut. There is also a simple plate that fits between the screw and the spring. Note that this plate uses 2mm of the available space for the spring.