Since the dust seems to have accumulated around the extruder gear, could it be that your daily “cold pulls” are scraping filament off onto the extruder assembly. The extruder doesn’t spin freely backwards, so that seems to be the most probable scenario going on here.
I had white powder build up in my extruder too. Turned out to be dust from a roll of white PLA. None of my other rolls have ever produced the dust.
I dont use a lot of bed glues as I love my textured PEI. When I do use glue, I spray a very small amount of 3DLac on the plate but apply it away from the printer to avoid any build up inside the chamber.
Does anybody use hairspray on the Cool plate?
I tried it last week and got real scared when the print all but refused to come off the build plate! Washed it clean with dish soap, reapplied glue stick and it’s back to normal. Your mileage may vary. Maybe I applied too much? Ida Know but I’ll stick with glue 
If it is too sticky, it probably means you did not apply enough aqua net hairspray. You need to put on more than a light dusting if the sheet has been recently washed.
The purpose for AquaNet is to hold the object when it is hot, and, to make it easy to release the object when it is cool.
If you don’t have enough spray, the object will stick too much to the plate when cool. So, the AquaNet is a release agent that helps with releasing.
I was wondering the same thing, that maybe he didn’t use enough hairspray. @Olias previously recommended using 3 light coats of hairspray. I have been doing 3 coats on the engineering and high temperature plate and it makes a very nice smooth surface.
I was actually wondering if the opposite problem would happen on the cool plate, that it would not stick well enough during printing because the plate doesn’t get hot, so doesn’t increase the hairspray’s holding capability.
I was looking around and read a few posts online about people using hairspray on the cool plate without issues.
When a PEI sheet has been washed it is clean and too sticky, I put on a pretty heavy coat of aqua net, perhaps 7 to 10 seconds. I’ve never seen any signs that putting it on heavy as a problem.
Then, after each print, I tend to spray just where the print had contact, including the test areas that the printer may lay down. I’m able to use the sheet 10 or even 30 times between washing.
I would say that I probably spray about three seconds after each print.
Again, the purpose is to be sticky when hot and to release when cold. The releasing process necessarily rips off some of the aqua which sticks to your model. That’s why if you wash the flat surface of your model, it will be slightly slippery where the AquaNet was.
My guess is that the release process is actually that some aquatic sticks to the model and some sticks to the bed and the separation occurs within the layer of AcquaNet itself.
Heavy applications will work to provide good adherence and release, but can also cause drips and runs, which show up on the surface of the print. Multiple “mist” coats, with time to dry between each coat, will provide usually a smoother surface.
I agree with @lkraus assessment. After each coat, the plate looks smoother and smoother, which makes the bottom of the print perfectly smooth. I have tried re-spraying the parts that have had hairspray removed from the prints, but this has caused some dots on the surface of the next print from the hairspray drops drying. I will try @Olias hairspray gluestick technique one day to touch up spots.
I may have gone too light. I did hit it 3 or 4 times and still did not have 100% coverage. I keep expecting it to apply like spray paint with a fairly even coverage such that after 3 light coats, the substrate can’t be seen but in the case of my can of Aquanet, I don’t get that unless I really go heavy.
When I say light coat, it is a fair amount heavier than a light spray paint coat. As you said, it doesn’t spray the same as spray paint.
I make sure that every coat is just heavy enough to cover all parts of the plate.
I see.
It looked more like orange peel wall texture than a solid coat. I may try again in the future but for now I’ll stick with glue stick. I’m still on the original that was supplied with the printer in January ‘22. Also, some scents trigger my asthma and Aquanet is in that spectrum so I have to leave the room while it bakes off the VOCs or run the bentobox plus the hepa filter. Once it’s cooked out, I don’t notice it at all.