I have two manuals, both dated 1997 but not the same; both also have (different) handwritten changes noted in them. Conclusion is that there were several variations, and yours is modified anyhow.
I could see a rebuild to better mechanical standards, especially since the components are mechanically different. But the Afterglow circuit has unique differences from what we do now which you may want to retain, if you really like the sound. (There may be some minor voltage optimizations to be done, once it is running properly again.)
I'll be out of town for a week or two, but happy to talk when I'm back. If nobody else comes through, I can copy one of my manuals for you.