For some reason, I got to thinking about "I Can't Make up My Mind" last night, and I realized that I hadn't figured out the bass part yet. I knew the chords though, so the bass part wasn't too hard to figure out. There's one phrase that I'm still a bit unsure of, but maybe that's just because it's different from all the others (they're all three- or four-note phrases, but that one has - I think - three pitches where the rest have only two).
I also figured out the little keyboard part during the solo. There's the first guitar phrase, which Argent sort of replies to, so it seems as if the solo is going to have this interplay between guitar and organ, but the rest of the organ part during the solo isn't very prominent.
I followed my last recording and used electric piano, but now I think that it's actually organ all the way through.