The filament detection monitor is still under development. Rather than instructions for installation, you will find development progress here. The filament monitor is working well - switching between all 5 tools and extruding 12mm from each, there is a deviation of about 10% between tools. This is very good, and will easily allow detection of jams as well as filament-out.
However, the concept that allows it to read so accurately is also causing an issue. Rather than detect the filament directly, we decided to detect the idler wheel of the extruder, which reliably tracks filament movement. This has one great advantage: the signal that the sensor reads does not vary due to material opacity and surface finish; instead the sensor is always looking for movement on exactly the same surface. This allows for greater repeatability, however it depends on the idler not turning when filament runs out. The latest Flexion extruder arm has a strong spring pushing the idler wheel against the drive roller. So even without filament, the idler turns. The next version of the arm will have an adjustable stop to prevent this while still allowing plenty of compression on soft filaments. If that works, the filament sensor will be ready for sale.