If you start with something like acetone/ATF mix, if it doesn't work, then the acids will never work either since the surfaces are coated. If you start with an acid, and it doesn't work, you will have acid inside a joint still doing its thing. Hmmm. You can work your way up from safe-ish acids like vinegar. Also, vinegar is the best for removing aluminum oxide, either as paint prep or to release stuck parts. So yeah, that.
Oh, fuck, I just realized I'm recommending vinegar instead of acetone AGAIN.