Tried the scotchbrite again while brazing up the chain stays, flows quite a bit nicer. I also used less flux.. have FAR fewer pin holes. As to the old fillets not wetting out, I made a much hotter flame leaning more on the oxy and finnnnnnnnaaaalllly got it to wet out. Bonus points: got some of the sloppy spots to look much nicer =)

I have been so worried about putting too much heat on a joint that I think I'm actually not putting enough in the first place. My next goal is to get better at my edges so I don't need to lean on the file so much.