I know the title doesn't make sense, but i didn't know how else to word it; I'll try to explain as best I can.

I have a model that I'm trying to rig. The armature's in place, and I've parented it with auto-weights and done the necessary cleanup to make sure it deforms right. It works fine...except for some areas that move despite having no weight paint on them, and one area that doesn't move despite being colored bright red. They refuse to work, mocking me as I try to figure out what the hell is going on

I suspect it has to do with the way the vertex groups were handled when I first parented the armature, so I guess the question is, is there an easy way to fix the vertex groups, or do I have to go in and manually see which vertex is in which group now and set the weight accordingly?