Chased em trough quite a few times some bolt holes seem not to be filled with crap? N they spin down fine without to much resistance and come out with minimal or no gunk.. just wanna make sure it's fine to proceed ?
I back it up with a nylon rifle brush in my cordless drill, spin slow with a little light oil in the hole and you can pump them clean. Then dry them out with some carb cleaner and some air through a small piece of brass tube from the hobby store.
I cut a groove, put the tip in some automotive grease, went in and out multiple times, and poured some thinner down the whole to break down the grease then blow it out with compressed air. Time consuming but works great