Okay...as far as I can remember, this is the sequence of Eureka brushrolls:
1950's and 1960's: the Disturbulator (basic brush roll with no beater bars, but several rows of differently spaced bristle bunches)
1973: Hoover's beater bar patent runs out and Eureka introduces the Vibra Groomer which is an aluminum brush roll in a helix shape featuring two steel beater bars and two stretches of replaceable bristles. The steel beater bars are smooth with no indentations or breaks.
Late 1970's: Eureka introduces the Vibra Groomer II, which is similar to the original VG, except the two long beater bars have been replaced by several smaller mini bars lined up in curved row. The brushroll is no longer helix in profile, but round like the Disturbulator, and it's no longer aluminum, but shiny steel.
Early 1980's: Eureka introduces the Vibra Groomer III in their Express Power Nozzle. This seems to have been designed to compete with Hoover's Quadraflex Agitator as it really has no beater bars, but all rows of bristles have reinforcers that keep the bristles stiff as they hit the carpet fibres.
Most of the low end Dial-A-Nap uprights of the 1970's and 1980's had a simple wooden brushroll with one row of non-replaceable bristles, and on red plastic beater bar.
With the advent of the Bravo and Victory uprights featuring the motor set sideways (not downwards), and the drive belt to one side of the action end of the vac, the Vibra Groomers disappeared, and Eureka gave you basic plastic all bristle Disturbulators.
