Mike, on some Eureka canisters of various series the bump outs were circular vents that resembled fan blades; which I think may have been what were advertised as "fan-jet" motors. Eureka seems to have discontinued the fan-jet at some point in the 1970s after it increased the amperage of its motors.I checked again
with my reading glasses. 11.5 amps for the 1290. It has a slight round bump out on the bottom the diameter of the motor.
I think they increased airflow. I asked a former Eureka executive and he thought it was just a marketing term; albeit his mechanical aptitude may be more limited like mine. Eureka also advertised some cleaners as having dual exhaust with two standard jets on the bottom or at the rear which leads me to the airflow conclusion. Apparently the later motors with more amps negated the need for dual exhausts; as Eureka discontinued the design around the same time they were introduced.What actually did the fan-jet motors do? they probably did something for the suction, I hope.