Singer 457 Needle Position Selector Not Working?

I've repaired a Singer 457 that had a broken top gear. I have it re-timed and working, but the needle position selector (L-C-R) is "off" now; and zig-zag won't work. To sew a straight stitch, I have to put the selector in the "R" position which actually puts the needle in the center. When I move the selector to "C", the needle goes all the way to the left. I've tried loosening and re-adjusting the screws that hold the needle selector lever to the thin copper tab; but that didn't help.

Thanks in advance for any suggestions!