It would be tedious work, but it would be possible to make that eccentric adjuster from a pan head machine screw chucked into a drill press, and do some careful filing to create the offset to move the ground point bracket. You would need to file or grind the threads off the screw so it's a snug fit in the hole in the breaker plate, file the eccentric on the screw head by hand, and peen the screw shank to the back of the breaker plate once the eccentric is shaped correctly. That's sort of "Gunsmithing 101"- - - -hand-filing bits and pieces for antique gun repairs involving scarce or nonexistent parts.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!