Every couple weeks I do a full disassembly and brush/qtip cleaning of my grinder. Usually when I run out of beans and it's time to start a new bag.
After reassembly, I like to top off the cleaning with some compressed air in the intake, just to catch any stray bits that I missed.
I ran out of compressed air about a month ago and never got around to buying another can.
I have also been trying different dose/grind/etc settings to try and reduce some unpleasant bitterness. I thought my machine was scaled, grinder belt loosening, etc.
I also lowered my extraction ratio from 100% -> 65% and started stirring my espresso. This seemed to finally do the trick and my espresso is pretty rockin' right now.
Today I looked for some amazon-prime compressed air, and all of them have complaints about "bitterants" Apparently, they have been adding a bitter flavoring chemical to compressed air cans in order to prevent illicit use and also leaves a bitter residue on whatever it's used on!
After slapping my forehead I started typing this post. Hopefully I'm not the only one with a red forehead! (I didn't find anyone using the word "bitterant" before on this forum)
Darmok and Jalad at Tanagra