Ah, so a lip or tab on the grip that slips under the side plate must've broken off (since the screws look like they've never been messed with). Well, I do have a block of walnut sitting around doing nothing...
I wonder if the timing can be revived in any way (again, it looks worn, not deformed). I dunno, TIG-ing a little blob back onto the timing star and hand then whittling them back down to where it cams properly? I suspect the pawl spring may be weak/broken (hammer seems like it releases way too early) and that could the real factor in the timing problems.
"I don't believe that the men of the distant past were any wiser than we are today. But it does seem that their science and technology were able to accomplish much grander things."
-- Alex Rosewater