You can upgrade your Printrbot 3d printer with 3d printed version of newer direct drive aluminum extruder design. This extruder allows easier filament loading, more visibility when diagnosing jams and filament breaks and other operations.
All the files can be found at:
http://www.thingiverse.com/thing:281015
It is based on:
https://printrbot.com/2014/01/23/aluminum-extruder-documentation-fun/