I was surprised to find that this is only the second time I've recorded "Nothing's Changed." I'm pretty sure the electric piano part isn't super accurate, but I am confident about the A# G# F# phrase. I hadn't noticed until recently that "Nothing's Changed" has both organ and electric piano. I don't think the parts overlap anywhere, so it seems that Rod Argent switched instruments while they were recording and that one wasn't overdubbed (although genius player that he is, he probably could have played two keyboards simultaneously anyway, as he has in some recent live versions of "Time of the Season").
I still find myself marveling that they didn't use the alternate take that appears on the third disc of Zombie Heaven. The solo in that version is much better.