Extruder gear cleaning

I have had quite a few prints ruined by the hobbed drive gear on the extruder getting blocked. Cleaning is possible but never easy, requiring at least the removal of the idler and filament. A passage under the hobbed gear will allow access to a tube brush (bottle brush) and compressed air to clean it out - even when it is in use. Picture below shows a ghosted view of an extruder I have built with this passage in place



Brass and steel tube brushes are commonly available in diameters down to 8mm. I think that the passage may have to be lined with metal as the cleaning brushes are very ecffective at removing plastic.

Mike