Clean those Hobbs

The upgraded ebay hobb with the deeper, more concave grooves, plus the oiler addition certainly makes for trouble free extrusion. Well that was up until yesterday when I began having filament stoppages in the middle of a print. My first response was to examine the filament between the hobb and the hotend, but it was not bunching-up or kinking. Next response was to increase extrusion temp a bit and try again, but still no change. A blockage in the nozzle it must be I thought, so armed with a high E electric guitar string, I heated-up the hotend and tried clearing the nozzle. Still no luck!
Just for giggles I changed out the Hobbed Bolt for another and voila, problem solved!
Had a look under the microscope at the hobb which I had taken out, sure enough, the grooves were very much clogged-up with filament/oil debris.
I used a sewing needle and individually cleaned each groove as my tiny steel brush was not getting all of it.
So, I guess cleaning those hobbs is another maintenance chore to add to the list.
Hope this bit of info is of use to someone.

Yes all this debris came from one hobbed bolt:

 

I use a scalpell to clean the grooves frequently. Further I have recognized that the moveable extruder part - the one with the roller which pushes the filament against the hobbed bolt, touched already the opposite extruder frame. This resulted to inadequate pressure. So I modified this part by cutting the related filament guides...