You mention that you are having similar residue being left inside the extruder and nozzle correct? And you have mentioned that you have not used wood fill previously for any printing? The residue you describe is similar to that of what I have/had found which was a mixture depending on “deposit” of the residue consisting of being light goldish to a brighter yellow color. If so this leads me to two conclusions; these residues are completely unrelated and separate incidents, or the wood fill didn’t contribute to the residue and was in fact a direct result of another filament.
Bear with me it is in fact conclusion number two and there is another cause with the residue. It was stated that you currently possess three types of filament: Abs, PLA, HIPS. I have myself printed very little to none PLA which would remove the possibility of any contribution. The ABS that I use is black which would also remove its possibility of contribution which would leave HIPS. The HIPS that I was using was in fact a yellow color which could of contributed to the clogs which is also backed by the timing of the clogs ranging around the first usage of the HIPS. May I ask what color HIPS you were using? If the HIPS is causing the clog this could be due to a filament “coating” that is left behind from manufacturing that is turning the melted filament into a near glue consistency. This could explain why when my nozzle was soaked in the HIPS melting chemical (forgot name) there was residue still sticking into the nozzle. Perhaps a type of powder or spray is being transfer from the bags that vacuum seal the filament roll. Hope this helps, Prime.
The idler doesn’t need to be super tight if the extruder is aligned… If too tight, the hobbed bolt will leave “teeth marks” on the filament which may “catch” inside the extruder. Also ckheck that the bearing in the idler is rotating freely.
Regarding the alignment, a bamboo skewer may be just the right size. The other thing that comes to mind is a carbon fiber rods available at most hobby shops which sell RC planes. Bring a spare hotend and check the various diameters. Here’s a link for a 3mm O.D. rod: https://goodwinds.com/20079.html
Cheaper fiberglass alternative: https://goodwinds.com/fiberglass/solid-fiberglass.html