On the partsbuilt.com site, a filament related item caught my eye - https://www.partsbuilt.com/cleaning-filament/ So I ordered the item (1.75 mm size) and have tried it on both the C2 and R2 printers. Procedure - before loading a new filament: 1) Tap the Temp Control button and then the Extruder button. Set the temperature to 230 C and wait for it to warm up. 2) Remove the Teflon tube and Extruder cover. Insert a purge stick into the Extruder as far as it will go. 3) Tap the Back arrow icons (upper left of the screen) to return to the Printer menu. Tap the Motor Control button and then the Switch icon located at the upper right of the screen. This will switch between the X,Y,Z motors and the Extruder. 4) Tap the length button to set it to 100 mm and then tap the Extrude button only once! 5) Once the Extruder finishes movement, tap the Retract button a couple of times. Remove the remaining portion of the purge stick. 6) Tap the Back arrow icons to get to the Printer menu. Go back into the Temp Control menu and then the Extruder. Tap the Cooldown button. 7) Lastly, Tap the Back arrow icons to get back to the Printer menu. Go into the Utilities menu and load your filament via the Load Filament wizard.