Uhh... I've run Q21 quite a few times, and never have I had to pipe vinegar from underneath xylene. Unless he's changed it up, you should have no need of vinegar once you add base to your stuff. It seems to me as if you're not doing the tek properly.
Bring your PH back to 12, get the mash to a good consistency and pour the xylene over it warm. Stir is slowly being careful not to let the solvent become trapped in the mash, and remove before it starts to turn yellow or orange (or keep going if you want the messy stuff). Freeze precip. or evaporate the solvent. There should be no need or practical reason to shake anything or add vinegar to your solvent. You should have no problem with the tek as written and no need to deviate from it.
If you continue to have problems, Re-try the tek using the "fluffy white funfest" method for nn-DMT only, and proceed exactly as the instructions suggest.
Happy Trails.