The
Picture of the motor is a 1960 motor. Kirby models 515-sanitronic VII 1955-1964 armature isn't made for the 1951 511. The field coil looks post 515 era too.
I meant the last owner put this cluster in and realized it didn't work. If you put in a ds50-80 setup you mentioned you also would find it wouldn't work.
I have field coils and armatures that would fit your machine. If your interested let me know.