Best way is to coerce/cajole someone else to do it.
Take an oily or greasy, rag and place it around the area. Then scrape off the residue in that area. The oil/grease in the rag acts as an attractant, and grease will hold heavier particles than oil. So, when you remove the rag after scraping, all the scrapings come out with the rag.
For reaching into that area, a narrow putty knife will get the job done. The end of the knife will not be pointy. But, more like the back edge of the knife, and you will use it in similar fashion to a scraper. You will drag the scraper rather than push it. A dull scraper will frustrate. A sharp one will remove the aluminum, too. It's a skill to learn on how to use (and sharpen) tools.
