If any more of these machines turn up, we'll need a "sticky" post to keep them all in one place for future reference!

Fran
I had forgotten that I have a B-150 with grill.fran604g wrote: To me, it just looks as if an outer frame of larger dimensions was added to the existing III/150 grille to fit the larger Amberola I horn opening -- instead of the slightly smaller "frame" that would've been originally used.
The earliest 2-spring governor that I've observed had a slot milled into the governor sleeve, mated to a roller bearing fastened with a precision machine screw to the governor shaft -- thereby creating a "shock-proof" governor...meaning the start and stop torsional effects of the weights were less likely to cause bending and distortion to the governor weight springs and creating undesirable speed fluctuations to the motor.
I notice yours has 2 hemispherical weights; does it also have the roller bearing and milled governor sleeve?
I don't know how you manage to find these "gems", but kudos for finding them!
Best,
Fran